Well, I have a lot to learn to get things right.
The upgrade is maybe not the only problem for all these unassigned files as the same library in V21 now shows as many unassigned files.
I started digitizing my CD collection in flac format in V21. As the process was moving forward I could see the albums and artists populating the database called Flac Library. The whole collection is about 600 CDs. I am not sure what was the status of auto-import at the time but I would guess it was the default setting. My goal was to get the flac files only in the MC database no contamination with Wav or Mp3. Location of the media was on a separate drive and the media went to I:/My Music.
Later, I created a new Library called JP Library. Auto-import on the library was turned off. I ran an auto import manually pointing to the same location (I:/My Music). At this point the Flac Librariy and the Jp Library looked the same.
Then I started to add my Itune collection. The PC use for Itunes is a different unit so I copied the album files to I:/My Music on the MC server adding albums to existing artist's folder and creating new folder for artists that were new.
I then ran an auto-import to add the new .m4a material and the original flac to JP Library. Things looked OK.
Recently, just before the upgrade, I did the same exercise to add my mp3 to the JP Library. Mp3s are mainly used for an old Zen Media mp3 player. This library had the CD collection (wma and mp3) And some additional albums that only exist in mp3 format. I manually compared the my new location and the mp3 disk drive to add only the albums that are not part of the CD collection. These files have been added manually under the artist name in I:My Music or a folder was created if the artist was new.
I:/My Music now has my CD collection in flac, additional .m4a files from Itunes collection and mp3 material only existing in this format. I then ran an auto-import to update the database.
Here I am now restoring the JP library and finding hundreds of files that are unassigned, artists and albums unknown.
I don't mind redoing the work from scratch but I am missing some understanding on how to organize and validate that the naming convention and folder organisation that MC could understand. Strongly believe that the product is OK but my knowledge deficient.
The tree I use right now is I:/My Music/[Artist Name] / [Album Name] / [Song Name]
Please note that most unassigned files are flac and have been ripped with MC.
Sorry for the long post, but if there is a best practice for what I am trying to achieve, I am listening...
Thanks