Total Noob here, having this exact same issue. Not sure where I am going wrong with the scheduler.
I have 2 playlists -
"Bright" plays from 1700-1815.
"Dim" plays from 1815-0000. This does not stop at midnight, I have to manually end it every night.
I am running the newest version, 2017.42 (64bit)
When I run a check schedule, I only get errors about extra channels (which doesnt make sense, I've checked all my models, and all channels are accounted for).