All my mobs despawned

ALL my mobs are despawning. I've had two NAMED axolotls despawn, 3 tamed, saddled, and leashed horses despawn, and 4 tamed wolves despawn. This isn't that annoying for me, but I am annoyed about the horses (they were pretty good). I can't really include a screenshot because the mobs are already gone, and it wouldn't be a picture of much (also I had over 50 chickens despawn, and mobs that are about 2 chunks away are despawning).