@GoldenHelmet Took me about 20 minutes to get results on video.
https://1drv.ms/v/s!AvUc4QTheCC2-TNUq6Kf0ZC4iejm?e=3W5PXo
These are all the mobs in my immediate area. I wrote them all down in a book. You may need to pause as I went pretty fast as Xbox has a max record of 10 minutes at 720p. I didn't notice I lost my first llama in my test run prior, hence there being only 3 named ones and no 4th unnamed one. He had a green carpet equipped. Note the number of Sheep and Cows as, despite my theory, were the ones to vanish. 7 Sheep and 3 Cows. Ignore my return home at the end as I couldn't edit that out.
After I saved and quit and relogged in a different chunk this was my discovery.
https://1drv.ms/v/s!AvUc4QTheCC2-TLO2fSlifovNkz2
This is when I noticed the loss of the llama, also books sometimes change the display of the first page of text, often turning 'Enters' into 'Spaces' is irritating. But that's a different complaint.
I personally think this bug and the parent bug are similar, if not related, but are different as well. Before starting this demonstration, there was no mob despawn in 2 weeks of continuous play all across the world. To add named mobs without despawning others, I would travel out to a remote area where no named or tamed mobs were within sim distance. I then tracked down the desiresd mob and trapped it. I saved, quit and waited for the Realm to deload everything as no other players would be on. Once I thought enough time had passed I relogged. Now all tamed and named mobs would be in deloaded chunks. I'd then name the mob in question and work on bringing it back home. No mobs ever despawned during the two weeks of using this method. Not until my trial demo and my demo I recorded where I just named mobs without my arduous workaround.
I think there's something here that is really weird and I want to make sure this is investigated as much as the other one. I tried to provide as much info as I could because I know in bug testing it helps root out the issue.
@GoldenHelmet No villagers in the entire realm are named. I guarantee that naming any mob with multiple named mobs in loaded chucks causes a mob to despawn. And I've lost 90% of my turtles, they are my most lost due to the bug. The only turtles that have never despawned are the ones unnamed.
@GoldenHelmet This is an issue I experience regularly on my friend's realm. It's not exclusive to named mobs as my foxes, pigs, and mooshrooms as well as tamed horses and a Mending villager have vanished, but whatever bug is causing this, it seems to prefer named mobs over unnamed ones as unnamed turtles in my hatchery have never despawned but my named one have all despawned except one.
I'd send you the world save but we're both on Xbox and I'm not in a position to jump through hoops currently to get the save file. If there's a simpler option I'd give it try. Or I could give you access to the Realm to experiment on. We can always back the world up.
@GoldenHelmet I see. Well I hadn't noticed that. I never expected my farm animals to vanish so in my first run I guess I glossed over their low numbers. So my bad. I guess I should have payed more attention to my first results. But I appreciate the reopening of the report. I can confirm that some despawns are related to chunk borders and Nether travel. But not all of them. And with it difficult to consistently replicate but usually noticeable when it does, I just wanted to ensure that whatever is happening here isn't left unnoticed when fixing the other depawn bugs.
From my observations I have never lost any Wolves, Cats, Parrots or Skeleton Horses. But my friend, the Realm owner had a Wolf go missing about 700 blocks away from me. I don't know if it despawned or bugged out and teleported somewhere if another mob made it stand up by pushing it into water. No death message was noticed by either of us. Just an observation. I just hope the issue is resolved relatively soon. Thank you for taking the time to look into this.