The scenario. Two streams each with a newly created playlist. Both playlists have identical settings. One schedule works perfectly. The other constantly stops and reverts to the standard rotation.
The question is what can cause a scheduled playlist to falter. I have had to restart this problem playlist several times by altering the start time and duration.
Nothing fatal but would like to avoid such problems in the future.
Any explanation would be appreciated.

I can't really think of why this would be happening, but you can find out if you edit the station's settings, and, under the advanced tab activate the Nextsong Debugging option. This should activate Centova Cast's advanced debugging, which in turn should show us why Centova Cast has chosen the wrong songs.

After this, restart your station and the next time this happens check the nexstsong.log and see why Centova Cast chose a song from your other playlists, instead of the scheduled one.