Hi Kevin, it will also work without rotating it if the circle's center point is repositioned to be more exactly right on the bottom edge. Currently it's located something like 0.0013 units just very slightly above it, things that are barely grazing each other at just right around 0.001 units or so (which is the intersection tolerance) can be somewhat problematic in general.

In the attached version I've moved the cylinder and circle downwards to true them up so their centers are right on the same level as the bottom plane, this then should also work ok.

Generally what happens with this kind of barely grazing thing is that there's some teeny tiny little intersection piece generated and it's collapsed or back tracking in such a way to mess up the orientation of the trimming boundaries. If a trimming boundary has any self-intersections or backtracking little pieces in it, it makes it not have a well defined inside and outside region anymore and that's when you can see that weird "leakage" looking stuff.

- Michael