Same here!! Updated to firmware version 9.17 and now my music app does not work. The app will open and pair with my headphones, but pressing the "Play" button doesn't do anything. The forward/back buttons don't do anything either. WTH Garmin?
I'm Deezer user, in my case after update music controls were not working HOWEVER after re-authorization Deezer app (removing my Deezer account/music provider and adding back in watch) all works.
RESOLVED: I resolved this issue by uninstalling the Amazon Music app, reinstalling the app, re-registering the app, and then syncing the playlists again. The app is working now. Thanks for all the tips.
