Hi!! I've tried a few things, I hope this helps!
- It happens a bit randomly, but always after a few minutes after starting the app (like 5-10 mins).
- The black box is the same size as the "hit box" of the pet, so the pet tries to run but cannot move as it has a wall in front of it, but tries to move to both ways and to sleep, seems it makes normal life but not moving outside the black box. That black box does not move, if that appears somewhere in the screen then it'll freeze in that location with the pet doing its animations inside.
- It always starts when sleeping, so when the pet wakes up then the black box is there and cannot move. It is possible to restore its mobility and remove the box by selecting the "relocate pet" in the app icon (sometimes that's not needed, just getting the pointer over the icon without clicking nor selecting anything does the trick).
- I tried with default cat. No issue. I also changed the cat colors to custom ones and no issue either. It only happens with custom ferret colors as far as I know right now.
Thanks for taking care! This is a lovely app!