I had quite a few MP3 files marked as corrupt by Roon as well, but each played normally. Seeing the discussion and feedback here, and doing a little more research, I used MP3val.exe on Windows 10 to bulk scan and fix any corrupted MP3 files on my NAS.
I’ve only done spot checks of the most high-profile albums but, using the Focus “Corrupt” attribute, it seems like there are no longer any corrupt MP3 files. YMMV.