Mobs Despawn every time I log off

Anytime I log off of my world all mobs, hostile and non-hostile despawn. The villagers in my village are gone. My dogs, cats, and horses also gone. The horses often time have on horse armor and a saddle. I can be riding the horse and if I log off and come back on it is gone. If I cure villagers they also despawn. This started about one week ago. Thank you.