I have a design I'm attempting to generate. The first one I created was a little two small, so I was attempting to enlarge the design. In order to create the shape, I have to group two things together. When I do, errors appear to be generated in a section of the part generated with the thread generator. I downloaded the STL file, thinking maybe it was just a render bug, but it is there in the STL file too.
I don't know if this will point you to the design or not, since there doesn't seem to be any other links to it unless I edit it.