All mobs disappeared after update

All of my farms, all of my pets, my bees which I FINALLY got to spawn near my house, and hours of useless fishing for name tags gone.  Passive mobs have been despawning since the update, regardless of distance, have been disappearing, please fix it. I love the game but this makes it unplayable. It's an old world and my progress loss was devastating. I'll be taking a break until this is fixed.😞