I have 2 discs that are part of one album, but Roon thinks they are in fact two albums. Normally I’d just highlight the two and merge, but interestingly the metadata shows all of the tracks as being “Disc ?,” and I have yet to figure out how to correct that problem.
See screenshot… the other disc has the same “Disc ?” issue.
If you try and merge them as-is, you get the obvious warning…