Saving G-code to .nc file crashes CC

I have numbers of Carbide Create files and frequently use save-as to duplicate a working design and extend it. Today I have encountered a couple of files that have nothing more than a shape (a ukulele back) and they save fine in CC with edits but the file will not save a .nc file – it crashes CC.
I am running on windows 10 home on a PC with 12 GB memory. CC is build 312.
The project is for a Shapeoko 3 with material sized at 13,5 X 9.5 and a week ago this project worked fine with a stock size of 14X12. the clearance is at least a half inch on all sides. I cutting with a 1/8 bit on cardboard.
Is this crashing a common issue with CC?
Any suggestions?
thanks Roger

Updated to build 313 and the GCode file save stopped crashing CC.