Did you ever find a solution? I am still waiting for a solution.
Nope. The desktop (Mac) app works just fine. I can play Sonos Radio from that which then shows up as recently played in the iPhone app. When I try to restart a radio stream from that, it gives an error message.
My network storage music library has also gone completely as a source (from the app) but still plays from desktop.
In their efforts to give us ‘an Apple app experience’, team Sonos have fundamentally broken key functionality. Looks nice, doesn’t work. Well done Sonos.
I have the same issue regarding Sonos Radio. Computer works, phones and iPads do not. For library I use Synology NAS which supports smbv2,3 so no real issues except it used to be divided up by albums, songs and artists. Now it is just albums. I think a fix for that is due soon. I also have an Apple TC with other music that is no longer available on Sonos as it does not support any smb security. So it is a good idea for backups of other means. I just hope to resolve the Radio issue.
It is really too bad that handheld app (80.02.04) is not as good as the desktop version (16.2). They really should operate the same. There are still many functional and visual issues with 80.02.04. I guess only time will tell if all returns to normal.
In the meantime SONOS! Please fix Sonos radio authorization loop!