I have a survival realm and my horses keep despawning when I log out. The first time it happened, I logged out while riding my horse in the open. At first I thought it had just ran off, but I couldn't find it, even flying around in creative. The next time it happened, I made sure my horse couldn't escape by locking it in my friend's house and name tagging it. The only exit to the house was a 1*2 block door, so even if the door was left open, the horse wouldn't have been able to escape. Another player on my server is planning to start a horse business with me to sell horses to other players. He has a small pen with about 10 horses in them and he hasn't experienced any despawning issues. I've lost 2 saddles to this glitch and I want to know why it's happening.
Also, it's not an anarchy server and I've made it clear to my players that killing pets will result in an inventory clear and temporary ban, so I don't think anyone would kill the horses.