I would try removing SiriusXM from my Sonos, wait two minutes, then reinstall it, which would force a new ‘handshake’ with the SiriusXM servers. 

Kept going through all the steps to remove account and no dice. Followed @Airgetlam advice to wait a few minutes (waited about 10), then reattempted and now works. Hadn’t worked since firmware update made me setup everything a few weeks back. Great advice! Also, made sure to use SiriusXM streaming credentials and not account credentials. Was trying both until I read above advice.

Sonos just indicated that Sirius was no longer supported and to remove it from my Sonos app.

It is still listed in the service list, so I have tried to add it again.

The service add never completes and never gets past the service confirmation login to my Sirius account.

Now, I get a screen that the service is having problems and Sonos is working with Sirius on it.

Seems like there was some miscommunication, as far as I’m aware, there has been no change in the relationship between Sonos and SiriusXM, but it does make sense that there are some connection issues at the moment. As all Sonos ultimately does is point to a server that SiriusXM provides, and plays the content provided by that connection, it feels like the issue is on the SiriusXM side…but I don’t work for either company, so I’m making an assumption.