The usual cause of the results you describe would be a too stiff arrow, which would normally give you a nock-right, but instead impacts the riser and bounces back left. This would explain why you get the same results no matter what the point weight is: because it is the result of the bounce rather than the paradox. However, I would normally use a .400 spine bare shaft cut to 29” with a 55# bow, and a .390 spine bare shaft cut to 30” should be close enough that it should paradox rather than bounce. The PMA is cut past center, which should allow a considerable latitude of spine difference. However, just to eliminate the possibility that the arrow could be bouncing off the strike plate, you might want to try a .500 spine bare shaft and see what happens.