X-Carve Pro Not Cutting 'Square' Squares

I use the X-Carve Pro with Cabinetmaker to, well, built cabinets. Since starting this process, I noticed the cabinets are out of square when assembled. I was able to track the issue down to the individual cuts themselves being out of square. Every 12 inches are out of square by ~1/8 inch. This is huge when you are talking about 42 inch upper cabinets. Any ideas why the machine is cutting out of square and how to fix it?

Cut settings:

  • Birch plywood
  • 90in/min feed rate
  • 38in/min plunge
  • 0.125 in depth per pass using 1/4 inch downcut bit
  • 17300 rpm