We used to print and cut PhotoTex and it was a pain with our Roland. We learned that sharp corners were the biggest problem. Once we learned to fillet (Corel) or round all the inside and outside corners, it greatly improved the process even though it never works perfectly.
Also, try different angled blades and changing the cut speed as well. The faster the cut speed the more pressure required. I am guessing that 60 deg blades will work better but they also will dull quickly so you might order several.