I’ve updated it after your message but it’s still not working. But that’s ok. I can rotate it beforehand.
I just tested this, and it works properly for me. As Rick said, it has to be exactly a 90 degree multiple, so either you’d rotate by type 90 (or -90) into the rotate box, use the Ctrl key when drag-rotating to snap it, or just use the (comma) and (period) keys to rotate.
I only rotated by typing 90°. Funny thing is if I rotate it again (“legs in the air”) it’s working fine So it’s only bad on 90 and 270 position.
If you email me the file I can have a look - the tolerance I have set is pretty tight.
I uploaded it here https://imgur.com/LwCxpgt