What I expected to happen: I put my animals in pens, leave, and return to find them safely in their pens.

What actually happens: Every time I come home, cows are out of the pen, sheep are out of their pens, and sometimes they even get into each other's pens.

This had been fixed several versions ago, but the issue has since returned.

I noticed this happening in long, narrow pens with one block of air between fences, enclosed at one end by a wall and the other by a gate. Other pens may be affected, although I have yet to test it.