I have a PRS Alpha with a spindle and 2 air drills. I designed a drilling toolpath in PW today, selecting the top of the material as the Z zero point. When I ran the file, it was treating the top of the table as the Z zero point. I was able to work around it by setting the Zero 18mm (material thickness) above the top of the material. I was able to run the toolpath, but am not clear why it was happening. I'm working in mm if that factors in.