Hi Ken, I download from the radio to chirp and then export it to a cvs file, make changes, modifications, additions, etc. and then import it back into chirp and upload into the radio. Although I am fairly new, that is how I understand it is supposed to work. As I mentioned, I get an error when I try to export the radio download to a cvs file and the program fails. Let me know if this is not the way, or an easier way to program the radio.
You can export to a CSV file if you want, but it's not necessary and definitely not the easiest way to make changes. Just make changes right in CHIRP and then Radio->Upload the changes back to the radio.
That said, I do think you're hitting some bug in the export process, but until you reply on the issue you created with the image I asked for, I won't be able to tell for sure. After you download the file, File->Save, and then attach the resulting .img file to the issue so I can have a look.
--Dan