Spotify on Sonos Beam with Google Assistant

[Lozzfromoz]

I am trying to play music on my Sonos Beam using Google Assistant. I have a Spotify Premium account. When I ask assistant to play anything (song, playlist, artist) on Spotify, it initially says "sure, playing xxx" and then after a pause says, "sorry, the requested media content isn't available for your Spotify premium tier".

I am using an iPhone X for the setup. I've tried unlinking and relinking my Spotify account in both the Google Assistant and Sonos apps. I've tried deleting and reinstalling Google Assistant. I've tried disabling Google Assistant and then reenabling it. No dice! I was previously using Amazon Alexa with the Sonos Beam for a short time and Spotify was working fine (but I would prefer to be able to use Google Assistant for other reasons).

If I try to play music using Google Assistant through the app on the iPhone, it will open Spotify and go to the correct artist but not actually play the song.

Would really appreciate any suggestions.. it's driving me nuts!!