I checked this statistics tab, new for me. I saw that my Classical category has about half (100) discs that are "not clasical". I guess that those are the disks that had details missing or in the wrong place, which I fixed. And I guess that those are the ones that in the details page show "Genre" something else (for instance Symphony), or nothing. I don't need to fix anything, and don't know how. But if Mozart is classic, who is?