When I pause/stop my music on Apple Music, my Sonos is often not available anymore after to play through AirPlay. I have to close Apple Music a few times and my Sonos will be back online. Here is the latest diagnostic number: 1995294878.
If it could help... When I use the Sonos application on my iPhone, I never have any problems. It's always with Apple Music and AirPlay on my MacBook Pro.