I put this perfectly reasonable CBS Masterworks CD in my Roon library, and Roon apparently has never heard of it or anything like it!
That’s the curse of the compilation haunting you … 
But to be fair to Roon it knows something about the recordings munged together for this particular Masterworks edition:
It knows about the original recording (or almost that) … second row:
And it knows something about the other recording, too and maybe even about your compilation (!) - row 1 and row 8 :
Is there a tag I could set to this value to get Roon to recognize it?
You can set a catalog number tag (and probably one for UPC), see also here - but I don’t know if Roon uses this for its ID process.
From my experience it often helps to play around with the search key words one uses in Manual Search.
Here’s another one:
Pretty sure I don’t understand the cover art on that one.
That KB article mentions a “UPC”. The Discogs site gives these:
ASIN (CA, COM, DE, ES, FR, IT, JP, UK): B002K662I6
Barcode: 5099704478425
Label Code: LC 0149
Matrix / Runout: MDK-44784 12 C3 MASTERED BY DADC AUSTRIA
Other: 01-044784-10
Other (Disc ID): 720E2509
Other (Distribution Code): CB 701
Which, if any, would be the UPC?
The UPC (Universal Product Code) is the same as the barcode.
Try the Barcode. To be honest, I don’t think this will help but you never know …
[Too late, Willie beat me here 
]
So I go into Roon, edit the album, click the Edit Album tab (seems a bit duplicative), and scroll down to find “Product Code” and “Catalog Number”. I assume the UPC is the “Product Code”. Catalog number, I guess, would be MDK 44784.
And then hit, ‘Re-scan album", right? Tried it, no difference. I presume these albums are not in the Roon database, which I find kind of odd. I was thinking that someone sells digitized versions of music publishers’ catalogs, like Books In Print, and that Roon would have just consumed them whole to start with. Maybe it works differently in the music business.
As a rule of thumb: if you can’t find an album neither at allmusic nor at musicbrainz then Roon may not know it. Not sure about Tidal but if I remember it right metadata won’t get copied over from Tidal to local - at least not for non-Tidal users which I’m one of.
If you’re determined you could add albums you want to get identified to musicbrainz. But that’s quite some work - even so at least for the first album you were looking for most of the data already is in musicbrainz. That would be the luck of the compilation.