Sheep in my fenced area escape when I log into the game.

What I expected to happen was...:
The sheep would stay in the fenced area.

What actually happened was...:
I have several sheep in a pen (fenced area) on the surface. They are secure when I log off but when I log back into the game 1 or more is outside the fences. I have tried with and without a fence gate section and the issue is the same.

Steps to Reproduce:
1. Have sheep in a fenced area
2. Log off
3. Log in