When CMPro tries to do an in place rename of a file and the new name is too long for the operating system, it deletes the file. It looks like this happens when the path+filename exceeds around 260 characters.
It's not bug. You got the scanner advanced option enabled :"move not renamed sets to backup".So no matter if the filename is too long, if a rename operation fails, this option forces cmpro to move the file to cmpro's backup folder.Roman Scherzer