So at Z25 it’s perfect. The probe just barely slips right under the end mill. So it may just be the Z movement is slightly over shooting the incremental steps. I’ll have to look into Z adjustment for belt stretch or whatever may be causing it
But also yeah the probe is off at the circle by about 0.3 mm. It’s not a lot, but it’s not a perfect 25 all the way around. The little lip I thought I saw while measuring the 22 mm is just a fillet around the edge that ends before the lip.