An ACS is cut well past center, 3/16-inch,I believe, which means that the arrow has to clear more shelf width upon leaving the bow. That could be the cause of your problem.
Are you getting any porpoising in the arrow flight? You could be nocked too low, causing the arrow to hit the arrow shelf as it passes.
With that point weight, on a cut past center bow, you're on the edge of being underspined. If you haven't already, you might build out the side plate a little, i.e., put a piece of toothpick or match stick behind the velcro on the sight window. I build out the side plates on my ACSs that way such that when the arrow is on the string and resting on the shelf, the string will appear to be on the right side of the arrow point when viewed from behind. Just seem to get better arrow flight that way. If you don't build out the side plate, the string will bisect the arrow or appear to be on the left side of the point of the arrow. Those set ups require more spine, and the latter may not yield good arrow flight regardless of spine. Good luck.