I see your frustration now. Although this is a very nice program, trying to achieve this is a pain in the a… Roon has a lot going for it in many areas, but trying to categorize the music the way we want is difficult at best.
I do not know why only a certain number of songs show up in a album. This makes absolutely no sense at all. I can perform a search for an album, it locates this album which so happens to have 1407 MP3 songs and only 120 show up. I have re-tagged all of these MP3 files with the Same Album Name. One of this program strengths is Meta Data. They should All show up. I have 3000 WAV files and I have no problem seeing these at all.
When I first setup my files I only scanned for WAV and a few FLAC and had no problems. Did not scan for my MP3’s because they are of lower quality. However I do have 10s of thousands of MP3s and when trying to setup a Singles folder like you wanted for MP3s, then this just did not wanted to cooperate with the built in navigation system in place.
There is absolutely no way to navigate to a specific folder ie a tree view and play or bookmark this folder. Will keep trying to figure this navigation out. Keep you posted…