Running a 12x12 piece of acrylic in a UBC. The acrylic is 11.9x11.9 actual, while the project board is 11.75x11.75. I tell the machine to center on the board. Machine does not center on the board. It measures it perfectly, then puts the carving on the board - consistently - about 1/4" to the one side. It is so consistent that I finally just edited the project so the carving is off the side, and it comes out centered. Latest firmware, clean board sensor, I've gone over everything again and again, no answers. Any thoughts?