Lots of people seem to be reporting today no chromecast audio on Spotify. I can get audio from YouTube and other apps but when i chromecast Spotify the picture and song cover comes up and the counter ticks down but no audio.
Thanks for all of the reports. We've just heard back from the tech team, and can confirm that this has been fixed!
If you're still having trouble, we'd suggest following the steps here for a quick reinstall.