Its not a tuning problem guys, actually itsa common, its no different than an arrow hitting a limb.
Sometimes the arrow goes stright through, sometimes it deflects off of a rib or other bone. I shot one onetime that was a perfect broadside and the entrance hole was right in the pocket behind the shoulder where it should be, yet the exit hole was almost at the end of the ribs on the other side and I have never hunted with a untuned bow or arrow.