First, I'll ask the obvious question. Are you shooting down at at your target or is it at eye level?
If that's not it, could still be your nock point. If it's too low, the arrow can bounce off the shelf causing a nock high impact. If it's too high, it just flies in that orientation, also causing a nock high impact.
Are you shooting three under or split? What is your nock set at.
Could also be a form issue. You could be torquing the string, i.e., putting too much pressure on the string, either high or low in your three-finger grip.