m3u playlists in Serviio?

I have Serviio v1.7.1 deployed on a QNAP TS-231 with QTS 4.2.2 26/11/2016. I have a number of m3u playlist files stored in a Playlists folder in the path of the Music folder where all my audio media is stored. I do not seem to be able to access these playlist files and use them for playing media. Does anyone have any suggestions on what to check?

[DenyAll]

Check this viewtopic.php?f=5&t=9368&hilit=playlist+qnap
If that doesn't help, post the playlist and a log after you add a playlist file.

[atc98092]

My experience with m3u playlists has been hit or miss. I seem to have better success with .pls files.