I think this is the problem I'm having, too.
If I open my mbl file in notepad, all the file paths correctly point to my K drive where the files are, but on opening musicbee i get a long list of these:
6/20/2016 2:24:10 PM - startup monitored folder:: dead file link removed: K:\Lenovo T420\Music\Music Library\Art Tatum\1949-1953 {Chronological Classics, 1411}\16 Elegie.mp3
But the files are all in that location! I also sort by date added, and my playlists (which all open correctly, but without any files in them!) are very very important to me. Surely there must be something that I can do to keep those two things? For the future, im going to set up autotagging to write the date added information into the file's tags, but I don't want to lose all my past information if possible.