Ок, thanks, I think I need to reauthorise

Nope, all working here, maybe try setting up the service using another controller device, if you have one to hand and just ensure it meets these system requirements:

https://support.sonos.com/en-us/article/sonos-app-requirements

Also try a reboot of the network and Sonos devices.

If using an Apple controller, you could also perhaps try logging out/in of ‘Media & Purchases’ in the iOS device settings.