I used to get that 'not available' thing from Tidal also, even inside of Roon. But I'm not sure it's because the recording is removed. There's no good reason to remove tracks from Tidal (besides they haven't paid royalties in 6 months.) I think I read something about the problem in a Roon support forum post, but I don't remember what it said. Probably something useful like "Reboot your Windows and try again when the weather changes." Hopefully your favorites come back Tom!
Listening to the RR this morning. The recording quality is great in RR tradition, but there is too much church reverb, and the music itself isn't really all that interesting, even by religious choral music standards, imo. ymmv