Hey, not sure if it's a bug or not, but at least for the basic prosthetics workbench when you prioritize your worker he doesn't really prioritize like any normal job. He sometimes stops at the middle not even finishing -one- item (even an eyepatch) or creates one and goes away (even if it's 1/10 needed to be completed).

So I don't know if it's a bug or not, but I assumed it to be such because prioritizing in the game is different in any other place.