Hi Tony,

Just tried to replicate your issue here. I added a folder from my NAS into my Mezzmo library. All files were picked up and were added to the smart playlists and active playlists. Then I added a new file to the folder on my NAS and went back to Mezzmo and browsed the folder. Mezzmo picked up the new file and the new file was added to smart playlists and active playlists.

Can you tell us what you are doing so we can replicate the problem here? Perhaps take a screenshot of the Maintain Library dialog so we can see your maintenance settings.