I suddenly lost all music services and was not able to even re-add any.
I read a bunch of possible solutions such as rebooting the router, reinstalling the app etc.
I opted for the simplest solution which was to simply reboot the Sonos system. Now I have 8 Sonos amps not a play speaker so not necessarily that easy I thought. But all I did was unplug one and plug it back in. Waited 1 minute for it to fully reboot. Magically all services magically reappeared.