Hi Yenmonger, thanks for reporting this bug - that is kind of weird that it works in one direction and not the other but it does seem to be a side effect of that area that Brian shows above - the bottom curve of the shape is a polyline made up of 3 segments and the middle line segment is a really teeny tiny little line piece and that's having a bad effect on the whole operation.

In the attached version I've put just a single line across that bottom area and now it should behave normally.

- Michael