I'm having a lot of problems adding services to my Sonos system. Plex, Soundcloud, tune in, Mixcloud, pocketcasts and probably more. I'll get to the place where I'm taken to the website to authorize the service. In each case, I'll login and then the webpage tells me I've been authorized and connected to sonos. I then go back to the Sonos app and it says “Connection Error. There was a problem adding the Mixcloud account. A connection to Mixcloud could not be made.”
With Soundcloud I have to enter in a code which the website tells me is ok. I think Plex requires a higher subscription so that's probably why it didn't work. The others should connect, I successfully use them on a different Sonos 1 system (which is at a different home and a different network and the old S1 app).
I was able to add the CBC music service.