Despawning or clear Problem of Mobs who can't despawn

Hello, I’ve found a bug with elytra. When I fly from one area to another mobs have the tendency to despawn (particularly those who I interacted with). A Villager disappeared and also my horse, that was wearing diamond armor. I’m sorry that I’m reporting this problem again but last time I reported it, I don’t think you understood what I meant. I want to mention it again so you don’t misunderstand, mobs with whom I’ve interacted with (named or traded with) are constantly despawning. As specified the isn’t supposed to allow that to happen. I hope you can help.