Villagers and Minecarts (possibly other entities) are disappearing after Logging Out.

@unknown: I assume that uploaded world is the "before" copy. I can get started on trying to reproduce the problem as soon as you tell us what to expect upon opening it. (Do mobs disappear in front of your eyes? Do you need to go somewhere and come back? Might I need to try several times? How long should I wait for it to happen before I give up and try again?)

This is happening non stop on my realms - the last 3 times I have logged in I only have 2 adult villagers and the rest are gone. They are named and traded with every time. Same with a golem. I am now on my 9th time making and naming a golem only for it to be gone when I log in. I am paying money for this to not be fixed.  

Auldrick, sorry for doing this piecemeal..., but yes, you're right.  that first file

Disappearingtest-baseline-2100-16FEB.zip was a before view.

Tonight we were able to get at least 3 librarians on the Realm, with good Books.  One is a Efficiency 5, one is Silk touch and Mending, and one is a Sharpness 5.

There are signs in front of their cubicles showing what they have, and that they got that on 17 FEB.

Because I dont know if there is a difference in the backup made 20 minutes before I logged off, and a download made after I logged off, i'm providing both of those files as well:

• 2314-17FEB-Librarians.zip   was made from a Backup dated 23:14:23 on 17 FEB

• 2350-17FEB-Download-Librians.zip  was made from the "download world" process at 23:50

I've logged off for the night, and we'll see who's there when I log back in.  If anyone is missing, i will do a save and download that file and provide it.

As to what to expect.

We have not had villagers disappear in front of us, or even while we were logged on.  We do no expect anything weird to happen while it is open/you are on.

If the bug is evident, it will be in that there are not 3 librarians in the library, in the town in the vicinity of -240, 384

The standard way this bug has presented itself, is

• operations as usual when logged on and playing, you put time into making librarians/minecarts

• you log off the realm

• upon returning and logging back in to the Realm (usually after several hours) 

  • sometimes 'some' villagers/minecarts are missing

  • sometimes none are missing

When we have experienced it since the update, it has been almost every day.

I've downloaded all three of your attached worlds to my PC and inspected them as local worlds. I think we may have had a miscommunication somewhere.

Your "baseline" world, although it's only from a day earlier, is clearly from too long before the 2314 backup, since you haven't even begun to build the earthen wall or cubicles for the librarians yet. What I was hoping for was a backup from just before several librarians disappeared, that is, one where the full number of them are present. I see the three librarians you're talking about in the 2314 world, in their cubicles with signs, and also a baby they made because there's an extra bed in one cubicle. There are four other cubicles, one of which contains a black sheep; are those where you were keeping librarians that disappeared? If so, then I need a copy of the backup when they were still there. I'm trying to reproduce your experience of the disappearing librarians. I can't do that from the baseline world, where they don't even exist yet, and I can't do it from the 2314 world, where they've already disappeared.

Nevertheless, I tried to make the best of it by uploading the 2314 world to my own Realm, hoping that maybe more librarians (or even other villagers) might disappear. To encourage the disappearance, I spawned an additional 20 cows in the general public area of the village (that is, not within the cow pen) in case the issue might be related to the general mob cap. I then repeatedly joined the Realm about 6 times. As far as I can see, no mobs have disappeared.

I waited overnight and tried again. Still no disappearances. Quit and joined again a few times, but no luck. I will continue trying sporadically throughout the day.

If possible, could you please attach a backup from before 2314 where you already had librarians (or other mobs) that disappeared later? That's what I really need to hopefully reproduce the problem.

Auldrick, the miscommunication may be on my end.  This is not the realm we previously experienced it in, because we have lost track of who was there when on what day.  
These files are from a NEW TEST REALM we started just to try to reproduce this bug.

As soon as we get a librarian that disappears, we will pull that download and add it.

I did log on a little while ago, and all of the librarians were still present.  made a couple more, and locked them in with good books, and logged out of the realm.  we'll see when we get back.

As to the realm that we experienced this on first (both before and after 1.18.10), I can attempt to provide you with backups from that world, however I doubt that i would be able to direct you to see
Librarian X was there in backup 1, and Librarian X was missing in Backup 2...which is why we're attempting to do this test realm. 

Ok, very good. I'll be more patient.

Idk if this helps but for me: Realms never made a backup of just before my villagers disappeared. It happened twice now. But the second time was cured zombie villagers. All three are gone but I have no back up of them when I found them (or after when I had them) trapped them and then cured them. (I did this all in one session.) I just have a backup of before I went out and found any. It's like, their disappearamce is linked to "false" sessions of game play that didn't even backup. Regardless if it's realms or not. I can do what Married is trying to do (since I don't play on it right now bc of the bug) and see if I can't get it to happen again but it's so crazily unpredictable. At least since we have no idea what makes it happen yet.

@unknown: I understand that you have no such backup because you collected and cured the zombie villagers in an earlier part of the same session they disappeared in. That isn't surprising and is norma. But as in Married's case, sometimes a backup is available that was known to be a precursor of the disappearance, and that's simply my best shot at reproducing this problem, so that's what I'm asking for.

If you want to get in on being part of this effort, I'd be grateful for your help. Repeating the instructions I gave earlier, what I need is a copy of the backup prior to the session where mobs disappeared and a list of any significant tasks you did in that session, such as journeying away from the area where the mobs were, plus any additional notes of anything that struck you as unexpected. If available, it would also be helpful to have a copy of the first backup after the disappearance, and to know when and where any other players came and went during the session and where they were.

@unknown: Your comment was automatically restricted to staff (and to you as the report creator) because you included an email address. No one else can see your private information. However, we never ask for personal information and it would be better if you don't include it. If we decide that working more interactively with you is necessary, we would do that via the Mojira Discord or subreddit. As for accessing your Realm, we would have to have an invite just like anybody else. That's also true for Mojang employees, by the way.

Yes, it's quite possible that mobs spawned under 1.18.2 are broken in a way that could allow them to disappear under 1.18.10, but mobs newly spawned (or made persistent) in 1.18.10 would be immune. That being the case, we should suspend putting a lot more effort into this until we have the proof that new mobs can still disappear. Unfortunately, this implies that older mobs might continue disappearing as you return to the chunks they're located in. I don't think that can be fixed.

So what we should do at this point is watch for a mob that was spawned in the 1.18.10 release and that subsequently disappears. If that happens, we can go back to the approach we've been pursuing. Otherwise, we could be beating a dead horse now.

You should also know that Mojang is still working on a fix for MCPE-21416, which is a very old disappearing mob bug report. I think they're getting pretty close to implementing it in the Beta, so the following release might fix this problem as well.

OK...slight problem....The files are too big to upload. 

I am going to try to put them on Google drive, and the link to download is at https://drive.google.com/drive/folders/1zPADCPWKXK1IN-FRdT0SdGgx4BnLnCiO?usp=sharing 

So in the files I just mentioned,  any villagers created on either 10, 11, or 12 FEB, were created after the update was applied, however the REALM itself is what i was referring to.  The TEST REALM was created after the .10 update, but the Mandallia SMP was created prior to the .10 update.

This is happening non stop on my realms - the last 3 times I have logged in I only have 2 adult villagers and the rest are gone. They are named and traded with every time. Same with a golem. I am now on my 9th time making and naming a golem only for it to be gone when I log in. I am paying money for this to not be fixed.  

Oops, my mistake. No, I don't think what release the Realm was created under is likely to make any difference. To make a difference that still affected the world after an update, it would have to store something in the world save that influences mob despawning, and I don't think there's any such information in the world save. On top of that, the most important determinant of whether a mob can despawn is its Persistent property, which is stored as part of the mob's data, so for the Realm version to be at fault you'd still need to explain why it only affects some identical mobs and not all of them.

I'll be studying your latest comments and world saves when I have some time.

Married in Minecraft: please open up the world save files on your google drive to public access so that we can download them.

HOLY COW! Sorry about that, and for not getting back to this until today.  Try it now, I think i've fixed it!

Auldrick, 

   I was reading Sara's comments on 

and the discussion about Chunk Borders.   I decided to go check the Library in Mandallia to see if any of the cubicles crossed chunk borders.

My wife just said that one of the librarians had disappeared from Cubicle 1 when she logged on around 11:00 PM EST tonight, but he was there earlier tonight (downloading he backups now)

  That librarians traversable blocks are 212-216 X, and 640-641 Z.
640 is in one chunk, and 641 is in another chunk.

Cubicle's 2 and 3 never had Librarians disappear, but both of those cubicles are completely in one chunk 

On the right side (as you come in the front door) the X coordinates are from 220-225.  
X224 is in one chunk, and X 225 is in a new chunk, so all of the cubicles on that side (4, 5, and 6) have an X chunk border in them....and all of the librarians on that side on the 1st floor disappeared!  

Will try to upload these backups as soon as they download to the Google Drive as before.

Close, but not quite. 640 and 641 are in the same chunk, as are 224 and 225. Every coordinate that is a multiple of 16 is on the west (X axis) or north (Z axis) edge of a chunk, and the chunk extends eastward/southward from there. BUT: If your cubicles are surrounded by a partial block such as a fence, it's possible a villager could move into that block. For example, if there is a fence at Z=639, I think a villager can get as close as 639.92, and in that case it's crossed into a different chunk.

OK, that makes sense...Files are uploaded to that google drive location.

Mandallia-23FEB22-2243.7z    Cubicle 1 should have 2 librarians.  @Badrabbit's xbox closed out due to inactivity

Mandallia-23FEB22-2310.7z - she logged back in around 11pm, and when she went back in, cubicle 1 only had 1 villager

Mandallia-24FEB22-0021 - i just included this download because it was the latest/most recent

Have just uploaded the fila Mandallia-26FEB.7z to that google drive location.

In it, you should see that both Librarians in cubicle 1 are missing now.

Life has gotten in the way, and I've been out of the net for about 2 weeks, but we're back now.  I'm told by others on the Realm, that while i was out there have been several instances of Villagers (named farmers and librarians) dissappearing, and sheep dissappearing, however have no files to show this, as...i wasnt here....

I have also experienced this bug playing in Realms. After the 1.18.1 release I came back to my base and found that all entities had disappeared from certain chunks. I had about 7-8 nametagged ravagers as well as a couple of llamas and horses confined in a one-chunk pen where they could not cross chunk borders. They were all gone from the chunk, just like experienced in MCPE-144208. I am playing on an iPad Pro. Let me know if there are any more details I can provide that would be helpful!

What we really would like to know now is whether any mobs that loaded correctly at least once since the 1.18.30 update have subsequently disappeared/despawned. The update released April 19. Some Realms may not have updated until a few days later.

@GoldenHelmet, just to make sure I understand the question, are you asking about

• a mob that existed prior to the 1.18.30 update,

• which was still there after the update,

• and subsequently is still there/has not disappeared

or 

• a mob that was created after the 1.18.30 update

• which has not disappeared

Both

• a mob that was there before and after the update, and

• a mob that was created after the update—

have any of these disappeared?

This is just to exclude any that may have failed to save before the update but were not noticed as missing until after. Those would be instances of the bug happening before the update, which we already know was happening then.