I’m having the same issue from the Sonos app so I’m assuming there’s issues somewhere effecting everybody. If I start the Amazon Music app and tell Alexa to play on my Beam it works. If I tell it to play on my One SL it won’t work. If I try to cast to either from the Amazon Music app it doesn’t work. 

And I just realized it works to either using AirPlay. So I can open the Amazon Music app and AirPlay to either of my Sonos devices. I would give that a try (if you have Apple product) until they fix the current issue with Sonos app.

This is really frustrating. I can’t see my playlists at all. Everything else gives the same error, “Requested Operation Failed”.

https://status.sonos.com/ There is a service problem. 
 

There are also several other threads about this. 

Well, that's good. When I looked this morning there was only the XM issue reported there.

Thank you!