Hmm....
You just shook the memory here, i don't use MasterCam, but Dolphin has a few different post processors for the
lathe, ie one for radius and one for diameter. So may be similar. Additionaly check if there is a turning mode that you can be in
when bringing in the file as that could just be a click and you may have mistakenly done it.
FWIW,
RICH