Animals and villagers keep randomly disappearing after relogging into game

I have an old survival world from 2016 that I transferred over from PS4 (through realms) and recently I've had a bunch of different animals and villagers disappearing, usually one by one. It seems to happen when I re-log into the game at seeming random intervals. So far, I've had 2 villagers, a sheep, and 2 horses. At first the only similarity was that they were all nametagged 4 to 5 years ago, but recently I've had a villager disappear that wasn't nametagged and I had bred less then a month ago. Reddit originally suggested that it was because they were located on a chunk boarder, but all the mobs have been in different locations (one was even in the nether!) Mobs that were on a lead have the lead stay wrapped around the fence with nothing attached (see picture). Is there any way to prevent this/revert it? 

Also, I regularly back up the file, and the backups seem to have the same issue.