I just spent 1 hour 55 minutes on the phone with Apple advisors, none of whom had Catalina or the new Music app on their work station. The third advisor screen-shared with me. We looked at multiple search functions that are no longer available in the new Music app, including the weak filter option discussed in this thread. The advisor agreed that, by comparison to iTunes, Music has been significantly hobbled, and suggested that I make a suggestion to Apple because, in his mind, they have to return the search and cross-referencing functions that worked so well in iTunes to Music. But the bottom line was that, according to the advisor, there is no way of getting back the kind of control/filtering we had in iTunes (yet). To be clear: the hidden Filter Field that has to be "shown" is virtually useless. I hate Music, and I hate that my ability to enjoy my music collection has been halved. The inability to use the Search function across the 5 limited categories under Library isn't just bad, it is infuriating, unnecessary, and among Apple's worst decisions.