I know there are some special considerations when dealing with a ZE on a Hoyt, but here are my thoughts (which may or may not apply):

How have you determined that the fletching is hitting, since you haven't seen any ill effects?

The broadheads wouldn't make a difference in arrow departure.

At what point does your stop screw hit the stop plate? The earlier it hits during the draw, the longer the hook stays up during the shot. The screw should be adjusted so that it only touches the plate near the very end of your draw. That will insure that the hook starts to drop soon after the string starts forward.