Manual Tags n Roon

I manually tagged an untitled album in Roon as Jazz, and it does not appear with other jazz albums, but in a category all it’s own.

Correct, the thing you added is a tag, not a genre. Tags are for user-driven organization (similar to how tags work in, say, Adobe Lightroom). Genres are an organization of content into a hierarchy provided by one of our metadata sources. They do not mix.

Then how can I manually identify an unidentified album as belonging to a particular genre?

We are working on more editing/grooming functionality in Roon, but for the time being, this is not supported.

Ok. I guess I’m surprised there isn’t any way to use the metadata already in a file.