Kidsonos and communitypschit solution worked for me last night ... except this morning all was broken and I had to go back into the Spotify desktop app and send music out to each of my zoneplayers again before I could do so from the Spotify mobile app. After doing that all is working fine again now. I can move music back and forth between ZP from within the mobile app so if there's a lock issue it is releasing OK at the moment and I can't immediately replicate it.
However, for me the option to click on a room and manage groups has disappeared from both the desktop and mobile Spotify apps in the last day or two. I suspect changes have been made in this area of code... certainly suspecting a bug.
No offence but if you hadn't even figured out that you had to sign into the Sonos app before encountering this problem then I don't know what you're doing with a Sonos setup. I've obviously signed into the Sonos app(!), reinstalled both the Sonos and Spotify apps, reauthorised Spotify in Sonos app, removed and re-added Spotify as a music service in Sonos... Still Spotify will simply not play to three of my Sonos speakers (though it will to one other), despite listing them as available devices.
Been out for 2hrs and it's broken again on coming back home. Something is not handling a time-out gracefully and then getting confused. Whether it's a Spotify or Sonos issue I'm not sure (quite possibly Sonos given other devices seem fine on Spotify and the awful new UI Sonos have just released for Android...). Will raise with Sonos support and reference this thread.
Not sure why this is showing Solved when google searching, clearly a problem with both apps not talking, with so many udates on both apps recently this was somehow expected.. sonos app went from average to complete non sense and spotify..well nothing changed except that now we are unable to send the music to sonos devices...guess the app support should resolve this issue promptly and try to maintain the current user base.. thank God i havent purchased the yearly subscription yet as this is for me a deal breaker.
Yep.... Same issue here. Sad to see this kind of problems with a device that costs about 1.5 avarage monthly sallaries here in Poland.
Untill they fix it I'll just keep using the Sonos app. Installed the Sonos app on my PC too. Sudgest you do the same untill they fix it. You can download the Sonos Desktop app from here https://www.sonos.com/en/controller-app