AC Fry

Might be, but I haven't done any updates recently.

This happens to me regularly with two blocks of floating string between two tripwire hooks inside my iron golem farm (golems land on hoppers, block of air above hoppers at the golems' feet, string above that to detect their presence, and blocks that suffocate them above that whenever the tripwire hooks are activated by a golem). Playing in 1.11.2 but not in realms. Just single player survival.

Haven't played snapshots enough, but when my whole herd of several dozed horses despawned in 1.6.2, it included both bred and not bred, saddled and unsaddled, horses that were fenced in and ones on leads. It was SSP.

I also commented on MC-19480, but wanted to repeat here that I had a whole herd of horses despawn out of my base. Some were in fences. Some were tied to posts. There were also two donkeys. I came back to base one time and they were all gone. I use 1.6.2 and go back and forth between using the world in SMP and on a server with my family. I synchronize the files between them.

I was playing 1.6.2, which I have been playing since it was release, without issue.

I had a whole herd of tamed horses just disappear, several with armor. Probably five were attached to posts. Most were inside a fenced area. Two donkeys disappeared as well. All leads disappeared. They were there last time I was in the chunks. I came back from a trip via nether portal and they were all gone, every single horse and donkey in the area. More than a little disappointing.