I lost all playlists too. Contacted Sonos support via live chat. They do not have a fix. ‘Please be patient’ is the best they can do. Nice!

I have S2 on an old iphone. Thank heavens it still works, although it will no longer access playlist content from one of my streaming services and will not ‘reauthorize’ that service unless I update the app… which would wipe out all of my playlists entirely.

So the short answer is, you are sheets out of luck until Sonos deigns to fix the problems with its new app. Which it does not seem to be in a big hurry to do.