Hi @Aaron_Turner ,
Are the file permissions by any chance wrong for that directory? It sounds like Roon might not have access to write to those files in particular.
It may be interesting to see what Roon logs show when the backup runs. Next time you encounter the issue, can you upload a manual set of your NAS Core logs (accessed via these instructions) to the following link and let us know?
https://workdrive.zohoexternal.com/collection/8i5239cc05950ac07456889838d9319545a82/external