When I update/save, receive error message: "The document was saved to a temporary file, but FM can't rename it to have the correct name. The newer version has an odd suffix" And indeed there are files with odd file extensions - New chapter.fm.D6B
In my experience, the odd file extensions are the result of Fm crashes. I suggest moving them to a temp folder (in case you need to dig into them for something) and see if your original files are intact. After a few rounds of edits, you should be able to delete the temp folder.
I am suspecting network drive permissions to be the culprit. I copied all files locally and the problems disappeared. I don't want to have to do this as SOP so I am hoping when I can nail down our network guys they will give us full permission.