I have backed up my bootcamp a few times successfully and the other day I actually needed the backup to restore, so I did so without any issues. Now After getting the windows to work again I wanted to go back to Catalina and make a fresh updated backup. But this time the backup starts scanning and then quickly switches to a message “Backup was created Successfully” and the file is just a few bytes in file size.
I made a 40 sec. video showing what I am seeing
It shouldn’t say it was successful when it failed like that. Can you send me the log at support@twocanoes.com? Also, try run CHKDSK to see if there was any filesystem errors.
tim
sure I can send the full log… I didn’t think about looking at it… but here is what I am seeing as I do a fresh one for you 
Current volume size: 199329263616 bytes (199330 MB)
2020-06-29T12:08:54-07:00:Scanning volume, 10.000500% complete
2020-06-29T12:09:03-07:00:Record 1104 has wrong SeqNo (117 <> 118)
Inode is corrupt (104913): Input/output error
definitely sounds like a drive issue. Try running CHKDSK: