In a two player game all the animals, villagers and mobs behave erratically or become invisible.

When playing a two player game and we are near each other all the villagers, animals and mobs behave erratically. They walk through walls, floors and fences, jump around or become invisible. It all started when you made the female upgrade "Alex" I tried it and it was a disaster! Ever since then we can't be near each other or the world goes crazy. When we're apart the creatures all behave normal again. I've enjoyed playing with my husband for 8 months and now we can't be in the same town or cave together.
I'm not sure what version this game is. We couldn't find that info anywhere.