You’re not doing anything wrong.  The new Sonos App update broke that ability on May 7th, 2024. You can still do Tidal Artist Radio directly through the Tidal App using airplay to any Sonos speakers that are new enough to have Apple Airplay capabilities. Same for Spotify. 

Amazed by how much stuff Sonos have broken in their new app. Next to useless now

I am totally lost without this feature. I live and breath playing artists radio. I don’t know if the sonos gods are monitoring this thread but if they are, I may be going back to Spotify if this is not a considered update. Playing Tidal artist radio….

pleez

Me too. Plus the run on and play similar tracks thing when an album finishes. You can try the casting feature in Tidal but it seems a bit temperamental for me. I've given up on the Sonos app and just Bluetooth to my Move speaker now. Doesn't help with my old speaker though. Will be looking for alternatives in the future as this is the second time Sonos have crippled something I paid good money for. Hope you find a solution.

Releasing this app without this capability in place is like Toyota releasing a new version of the Camry before figuring out how to ensure the windows can open and close…

Is there a fix scheduled to be released?

Artist radio is one of the most important features of streaming services. Seems wild to miss it during regression testing and to also not have a fix yet