You have to let Roon finish indexing and analyzing your library. Unlike MPD, which only reads embedded metadata, Roon builds a sonic signature of your music files to uniquely identify the content, regardless of how they are named or what's in the metadata (i.e. tags), if anything.
I think you were the one that mentioned you haven't really tagged your files; Roon is perfect for you, because it doesn't rely entirely on tags to index your music. Subsequent indexing/analysis is very fast, in my experience, once it's completed the initial scan.
Trust me... let it finish indexing and analyzing before you grade the overall experience.
HI Ken,
That sounds quite mystifying.... not sure why they would do that, and, for example, how it would distinguish various versions of the same song. I have rather different sounding versions of lets say live opera;s. If Roon where to analyse how they sounds (compare a live mono recording in the 1930/40's to a high res 2015 recording of the same Tristan), they would well come up with different names

listen to Neil Young on 10+ versions of the same song, and the only way to know they are the same song, is by reading the name and artist ...
btw, Roon says its analyzing i the background for crossfade, volume normalization and waveform displays. All things i don't care for (yet). Still, it takes such a long time if i enable it, something must be wrong. Or my Macbook air (1,7 ghz, I7, 8 gig mem) is just not up to it.
Importing the tracks went fine, so i guess im good now.
Thanks anyways, very helpful as always Ken, appreciated a lot!
Cheers,
Marius