For a long time now, when I go to a playlist made up entirely of local files either the entire playlist is grayed out or one or two of the songs is available while the rest of the album is missing. I never change the location of the files and they are in the folder that is imported with all of the other files. Over half of my local collection in playlists is missing and would rather not try recreate all of my playlists.
What used to work temporarily is moving files from one folder and back into it's original folder and then Spotify recognizes them again temporarily then after a while I would have to do this again.
I am considering cancelling my plan and going back to iTunes considering these issue has been going on for a long time.