In truth, neither of the screws really serve any purpose unless you’re using it with their reach reduction kit (or possibly their short reset kit). I actually read that somewhere but can’t seem to find the source at the moment. The upper screw is likely the cause of your loss of DA, it can keep the trigger from resetting properly.
I’ve installed three of them along with MCARBO’s spring kits and I typically use the shorter screw with some VC3 (or your choice of thread removable threadlocker) in the lower hole (just to fill it, but you can leave it out) and toss the longer screw in a bag in case I ever decide to try the kit mentioned above. Best to keep the upper hole completely open. Unfortunately, you might have to pull the trigger out to get it out at this point, I’m not sure there’s enough access once it’s installed. Anyway, that should fix your issue, if not, you’ve got something else going on.