I am writing from Japan at night in the Golden Week holidays. I have seen the same bug and reported to Japanese Mastercam Distributor on 14 Mar. (the day before Murlin posted at first.) But it is not reported to CNC yet. And then I was registered in this site on 23 April. I found that I cannot solidify cylinder surfaces made from "primitive cylinder". The modeling do not have a hole. When I make fillets between side and top,bottom, I succeeded to solidify. When I make a cylinder cut by plane passing through axis and added the plane surface, I succeeded to solidify the half-size cylinder. Murlin wrote: >X5 is having a problem stitching the flat trimmed surfs. I think there is a problem in not only flat surfs. Perhaps failure is when top and bottom are flat surfaces and side surfaces (not need single) are not fold.