Maybe I've found a bug. Have a look at the picture below.
It's a thick wall, split several times. The first split already looked strange, because it wasn't a perpendicular cut, but an oblique cut. When I split one half into even smaller parts, things got worse.
EDIT
However, when you move one of the parts of the wall, all parts return to their normal form, and the face of the wall closes.
For your information I attach the file .
Hans
