Homing Issue

[Wcantrell2020]

I have set my XYZ using $101-$102. If I tell them to move 200mm, they travel that distance. But when I try to zero them out to set up for a carve, that is creating errors. I either use a homing switch, or manually set it to the surface, zeroing out the z axis. I can do both to set the 0. But if I move the axis at all, and tell it to go back to 0, it is off. So if I set z to 0, then travel up 20mm, if I hit home, it goes back down 25mm, into the surface.