I dunno....it sounds like the arrow is flying sideways....if that makes sense......Any idea what your FOC is? If it's too light, perhaps the arrow is trying to "flip over."

Have you shot into different targets? It may just be a path of least resistance deal....they hit the target and snap sideways....

To test the stiff spine theory, turn up the poundage of the bow, if you are able.....Even 5 pounds will make a difference, and if that straightens them out, get a weaker arrow and turn the poundage back down.