Just tried version 0.4.2 and still have the same problem with some of my parts. I noticed that it always happens when I create an arc by push/pulling a circle that intersects other geometry, maybe an issue where the first or last segments of an arc are different lengths? Here’s a picture:
The circle on the left caused an error unless I exploded the arc before push/pull. Hopefully that helps.
edit: here’s another example. The circle on the left I drew a line intersecting the segment end points, which generated a cut part fine, but the one on the right gave an error.