as the title says, some mobs (spec. passive/tamed) are affected by a bug, here are the ones from my world:

1. Cats left sitting on previous version, all stood and followed the player upon opening the world.
2. Cats, horses, mules, chickens, and donkeys had all their lead disconnect and drop as an item upon opening the world.
3. Dogs seem to be unaffected by any of the two observances.