Did you also Clear Data in Settings>Apps>All>Google Drive? And then did you update the Google Drive app back to the most current version? That's the next thing I would try. Also, does the error occur with any file you try to upload, or only with one particular file?
I'm not sure a factory reset would do a whole lot, but it may be worth a try. I'm not too familiar with CyanogenMod, so hopefully someone else here can give you some good advice on backing up.