Not sure if this is a bug or not, but I'm trying to mirror a part in my drawing, and none of the 4 orientations give me the desired result. The only way to make it work is to select "Create opposite hand version" which creates a new part file, even though it is a simple flat plate (left and right should be exact same part). I've tried both bounding box center and center of mass options. Some parts work and some don't. Any ideas?