Mobs that shouldn't despawn are despawning.

Tamed mobs and villagers are despawning when I load the game up . Mobs that I know are affected by this are: tamed wolves, donkeys, horses, llamas ( both normal and trader llamas) villagers, and sheep. Boats are also affected . Boats only disappear when I get out of them. Any mobs still in the boat when I get out also disappears.