When you’re browsing Tidal in Roon, you’re seeing Roon’s Tidal database, not a direct pass through of what’s shown on Tidal – that’s why there’s so much more metadata, like recording dates, lyrics, links to composers, credits, etc.
This is also why Roon can sometimes be slightly behind Tidal when a brand new release comes out – our database is generated multiple times per week, but sometimes a new album will just barely miss the cutoff, and will show up in a day or two.
One of the trickiest parts of building Roon’s database is determining when albums (or artists) are equivalent. Sharing data across different versions of an album works great for your local files, because you get the same deep metadata when you have the standard CD as when you have, say, an obscure Japanese pressing with an extra disc of bonus tracks. And distinct data among the editions (like the remastering engineer) will still be applied correctly.
So with all that said, what you’re seeing here is actually a bug, and one that we’re going to address soon. We’ve seen that in some cases, multiple Tidal releases are being marked equivalent, which means they are shown as a single release in Roon.
While some differences between Tidal and Roon metadata is expected and even desirable (such as when Roon has better data or deeper linking), obviously the missing releases you’re seeing here is not what’s intended, and we have some work in this area kicking off soon.
It should also improve our handling of some known artist equivalence issues, like this (where two artist with the same name are erroneously considered the same) or [this] 2 (where a single artist is erroneously considered to be two distinct artists). (EDIT: currently cataloging and fixing these issues here)
Roon’s database is built to handle these cases properly, but the underlying data is still generated automatically and sometimes the algorithm needs fine tuning. When we make those changes, we work very carefully, exhaustively confirming there aren’t regressions. I know it sometimes seems quiet over in the metadata section, but we frequently schedule work based on what’s reported there, so if you see something, say something 
Thanks all!