I have a problem, when I make a cut in an overall plan (with part and screws), when I put the screws in "uncut" according to the standards and I import the threads, it sometimes happens that they have annoying graphical bugs.
I tried several times to recreate the cup, without success. I have created a small example that has a threading problem. (Attached)
In picture a section of my part: (You can see that the middle part contains too many and badly placed thread lines, while the other two have no thread line at all).