How do I prevent a jingle which fades out slowly from being followed by a song where the artist starts singing immediately?

Create a Sound Code. Name it something like: Voice Open  and apply itto the songs that are Voice Open.

Then, on the Non-Music/Jingle to the Sound Code tab and then click the Voice Open  sound code.

This then tells M1 to not schedule any jingle with that Sound Code clicked in next to any Song that also has that Sound Code.