I can't imagine it being your grip or form because you say you've had 4 different people shoot it all with the same results. So I guess I'm with gibblet in saying start looking at the bow for clearance issues. arrow/cables, arrow/sight gaurd. Just a suggestion. I'm sure no bow tech.

Another thought and I don't know if this would make a difference. Are your cables placed in the cable slide correctly. I don't know if this would even effect anything or not but just a thought.