Mobs in spawn chunks don't despawn, resulting in no mobs spawning anywhere else

(Edited twice... )

I noticed that this isn't the raid spawn rates one so I am putting this in, Below is what I originally put:

Concerning Jen Ivins comment: That also seems to be happening to me where I can't find many hostiles above ground. I think this issue for raid spawn rates is should be marked resolved but there is another that is open concerning this issue

Still a problem. The /kill@e solution does work, though it is not a viable solution for people who want to keep the villagers they've worked really hard to collect, or their pets. All those villagers you threw into your iron farm? Well they are going to disappear also. All the maps you had of your world nicely arranged on a wall - gone. So by all means, to people who just play basic Minecraft, yeah that is a solution. Not for people who have farms that rely on the entities that go away with /kill@e.
Edit: By the way, my mob cap was not filled when I checked that solution, though it did sort of solve the problem. My only conclusion is that somehow villagers, pets, and maps seem to be included into the hostile mob cap now. Which is asinine.
I knew going into it that the /kill@e command would do all the things I just said they would which is why I did use a backup of the world.

Is anyone working on this? Still a problem as of 19w4b.

Still happening in a brand new world on 19w04b. Checked it with an Ocean Monument. Had 1 guardian spawn in 10 minutes. The elder guardians were there of course.

Still present in 19w06a, mobs in overworld were spawning rarely since the beginning, however endermen in the End were spawning normally until yesterday, when suddenly we saw a massive drop in spawn rate and now there has been no new enderman since 2 hours ago.

Immediately after restarting the server, endermen starter spawning normally.

Please dont edit your comment with a new version, post a new comment if you can still recreate it in a newer version

That way we can preserve the ticket history

Might as well note that this seems to be highly influenced by direction of all things, the game forms no-spawn chunks but these chunk's locations are not static (manually respawning enemies repeatedly gradually increases possible spawning area it seems) and have a heavy weighting towards specific areas. Logging out and back in temporarily increases spawn rate, but the game will never spawn enemies in certain chunks and has reduced spawn rate in numerous chunks.

Going off in most directions will see nearly no "no-spawn" chunks while one specific direction (I believe negative x and positive z) will become chock full of no-spawn chunks.

hope this can help testing some. I want this bug fixed; it ruins difficulty and end-game farming methods.

My 2 cents here: it is still the case in 19w07a

I didn't edit my comment with a new version. I edited it with the correct version. I originally typed the wrong snapshot in my first comment.

Can confirm this is present in 19w07a; in both the overworld and the nether.

19w08a problem still remain.... mob spawn rate is too low... no mob in loaded chunk... rare in other far chunk... unplayable.. farm doesn't work anymore.... mob spawner is always empty... village don't breed yet....

19w08a and 19w08b have the problem. At least for me... it worked ok in 19w07a

Spawning rate is working fine. I'm using the scoreboard to count the number of hostile mobs currently loaded and at anytime it's close to the actual mob cap (which is 70 per 289 unique chunks loaded). Still sometimes I can see barely no mobs around. So what's happening? I investigated and by teleportation to random mobs I found out they are standing far away where no player is, not even the chunks are loaded. Still they register against the mob cap. I think it's related to the snapshot entities tracking capabilities which are very problematic at the moment, causing mobs duplication, or entities still tracked even after the chunks have been unloaded. MC-141484

Still having this issue in 19w08b. When will this be fixed? No zombies, skeletons or creepers spawning. Every other mobs spawn normally. 

Why hasnt this been assigned to anyone yet?

Relates to MC-144990 Monsters not spawning

Confirmed for 19w09a.

In 19w09a I came across a pillager outpost and there were no pillagers

Confirmed in 19w09a. But the reason of hostile mobs not spawning that often, is the issue with the render distance.
If you set the Render Distance to 11 or above, Hostile Mobs will be able to spawn frequently. And if you have it on 10 or lower, thats the reason why the Mobs are not able to spawn in that often.

Came across village, there wer multiple houses but one villager
19w09a

The mobs spawn in a new created world, but not in a world the is upgraded to a newer snapshot

Assign to someone?

Confirmed for 19w11a. This is a real problem for me, as I usually play on 4-5 chunks because of my computer. During a survival world, I must have explored at least 20 cave systems and a mineshaft, and I didn't see any hostile creatures (apart from the cage spawners). When I set the render distance to 11, it went back to normal.

I think it's because the game doesn't unload mobs with the chunks they are in, which makes the mob cap full, even though no mobs appear in the loaded chunks.

Since three snapshots ago, I had such an extreme low spawn rate when I upgrade the world. Only the raids spawn and the mobs in dungeons. All the non hostile mobs spawn but the hostile ones, quite rarely. 

Same ^^

Same here, can confirm for 19w11b, but the non-hostile mobs seem fine for me

Yep, this is still an issue in 19w11b. I've been running around in a desert, and have maybe found 1-2 hostile mobs.

Contrary to another comment above, I can't see any difference when increasing or decreasing my render distance.

In my survival world, which I started in 1.13 and upgraded to 18w49a (and is now in 19w11b)  has no zombie, skeletons and creepers, blaze and wither skeletons spawning. However, all non-hostile mobs and phantoms still spawn. When I copied my survival world and used the /kill @e command, there was still no change. However, when I used the same seed and started a new world, at first the above mobs were not spawning, after I used the /kill @e command, they started appearing normally.   This is my situation. 

This is starting to get complicated. Anything else that is happening out of the ordinary?

Something that I have noticed in 19w11b. Mobs were not spawning. /kill in game didn't change anything. I went to backup. I removed all the entities by editing the region files directly. Then hostile mobs starts spawning normally again. But it was in Spawn chunks. I left the Spawn Chunks. No mobs spawning again. I use the /kill command to get rid of about 60 hostile mobs still loaded in spawn chunks. Yet no mobs spawning for me at this stage. I reloaded and run a test again (I'm outside Spawn chunk and this is this screenshot:

Then I closed the world and edited the region files again. It appeared that the 60 mobs that I killed earlier were still in the spawn chunks data. Yet not loaded in game, but still counting towards the cap? I reloaded and mobs started spawning normally again. Then once I reach the Spawn chunk, the process repeat again: no mobs spawning if you travel outside of Spawn Chunks.
Also I notice: if you run the /kill command, it will kill the mobs in Spawn Chunks (but it won't make the mob spawning and they are still in region files). If you come back to Spawn Chunk by tp, you will see the mobs that you killed being displayed and immediately having their death animation. Eventually, if you sweep the whole area, you will see mobs appear with immediate death animation, and it will finally allow more mobs to spawn elsewhere. So all of this might be a whole issue with mobs registering.

I remember experiencing something like this. Mobs not complety dying could is the root of the problem. Could the reporter test this theory add this to the description?

19w11b

The only hostile mob I've been seeing in my game were Pillagers. Occasionally I'd see one other monster. I went as far as to standing in a swamp for 3 days and nights, just to be sure. Which in normal game yields quite the amount of slimes, and not one spawned. I had to go as far as to spawn 5 slime eggs to get slime, lol. It sorta sucks I had to do that, but I suppose that's the risk of playing early features.

The frequency of Pillagers and Traveling Merchants either needs tweaking or it's being affected by this bug. Because Merchants are everywhere, and I feel like I'm being harassed every other day by at least one Pillager. The amount of Llamas floating around my house from all the merchants that came and left...

Edit: Misnamed Pillager

Could a helper inform us of the state of this issue? It's been a while without any updates.

We don't know more than you do.

Could the mods do anything to get the devs attention?

I'm sure they are aware of this, but this is not something of high priority, because it's probably not a simple fix, and also because it's not even an issue when starting a fresh new world before going further in the game.
Also, continually posting useless comment won't help them to solve it faster. Please only post relevant information. Do not "flood". There are relevant information above that becomes now harder to be seen and is masked by useless comments. This is not a support platform btw and Mojang owes you nothing, this is a development version, so use it at your own responsibility only.

This also affects water mobs. I havent seen any squid, salmon or any other kind of fish.

Mob-spawning in general has become incredibly strange. I've build a squid-farm using ilamngo's design (checkerboard of sugar-cane with columns of water (and kelp) between them) and haven't seen a single squid spawning there in the last couple of snapshots (at least since 19w11a - before that it produced more than a stack of ink per minute). I also have a creeper-farm with 2 block high-spawning platforms (with trapdoors preventing any other mobs from spawning). And again: nearly zero spawns since 19w11a (i probably see a single creeper every couple of minutes - in 1.13.2 creepers are constantly spawning there).

All spawner-farms I have are working just fine, as does my slime-farm (and apparently my witch-farm - but i only checked it very briefly).

All in all, mob-spawning seems to be pretty badly broken at the moment. Or lets say: very, very weird.

Still an issue in 19w12b.

I also have this issue. In four hours of game play I've seen 1 creeper and 6 illagers.

Literally nothing spawns, only villagers are attached to houses, cats to villages, drowned to the underwater ruins. I'm playing on hard and still nothing spawned

Edit IMPORTANT: I've noticed that a little amount of mobs start to spawn at day 5 - 6

Edit IMPORTANT: I've noticed that a little amount of mobs start to spawn at day 5 - 6

So this could be related to local difficulty, which matches my experience in my world. Around the spawn chunks I'm able to find mobs pretty quickly. But exploring a new desert, I've come across maybe 1-2 hostile mobs in a whole night.

I had this exact same issue as well, it was very frustrating. I was able to fix it by starting a new world and copying over some of the files into the "region" folder into my save, through trial and error. Hope this helps

Confirmed for 19w13b.

 Steps to reproduce

1. Create a new superflat world (for the easiness, but also because mobs are more frequent the lower the altitude is).

2. Once in the game, don't move, and set the time to night.

3. Let the mobs build up, or use a repetitive command block to fill the cap.

4. Once it's done, then fly away from the area, very far away, very very far away.
   You will notice no more hostile mob, nor animal is spawning the more you travel. That's because they are still loaded in spawn chunks despise no player is nearby.

@unknown: I updated the ticket with your steps. Thanks!

Looking through some of the duplicate bugs, I can confirm this is related to the one dealing with Nether travel. After traveling through the Nether as a shortcut to get to my other outpost, after a couple of days all of the hostile mobs just stopped spawning. It continued this way no matter how many trips I made back a forth using the Nether portals as shortcuts. I returned through the Nether back to my original outpost and then made the trip manually. Not a short trip, but once night hit, the hostile mobs appeared to start spawning normally again.