MB will not display the tracks in Playlists

[paulwiel]

Hi:  MB is not displaying the tracks of some of my Playlists ("PL") which are stored as *m3u files in a separate Playlists Folder on my M-Drive.  MB continues to display the PL Name but not the constituent tracks (the PL is simply blank).  Oddly, when I click "Edit" in the Bar above the PL, MB will promptly list all the tracks in a side-bar...