Showing albums & tracks in Roon

I have just downloaded Bach’s Matthews Passion (101 tracks) from Linn (Studio Master). Roon just won’t recognise it & place it in the library. I also have a recording of Copland & Harris’s 3rd symphonies; for some reason the library has left off the first two tracks. Is there any way of manually fixing these things? (There may be more. . .)
In all other respects Roon is fantastic!

“There may be more. . .” Yes, I’ve discovered that the database shows a version of an album which will not play. When I show hidden albums I can find the one that plays. I’ve done “unhide” & hidden the one that won’t play. Now I cannot see either! The underlying problem is moving duplicates from iTunes. Roon still thinks they are there, I believe. Advice please.