watchOS 10 Music app: No way to choose Watch playlist as source instead of iPhone playlist.

There used to be an interface option in the watchOS 9 Music app to make music play from a Watch-based playlist instead of from your iPhone. This interface is gone, and more often than not, when you start listening to music on your Watch, it plays from your iPhone. Then you leave your iPhone at home while you’re out exercising and, all of a sudden, the music stops.

I haven’t found a way around it. If any of you are smarter than I (a distinct possibility), please let me know how to fix this.

Relevant context: I don’t use iCloud Music Library or Apple Music, the service. This is all with music from my library, synced from my Mac, stored on my iPhone, loaded in my Watch.

It’s maddening.