I've come across this problem several times, and cannot figure out why it appears. When I make a drawing from an assembly, with mulitple screws in an exploded view, sometimes some of the screws do not show the thread on the screw, while other screws in the same view show the threads just fine. Has anyone come across this before, or perhaps even knows a fix for it? I've attached a .jpeg of the screw without thread lines in a drawing. Thanks for your help!