I'm getting a greyed out option for my Chromecast Audio device (it says "Can't play this right now") and I'm not sure why. My desktop can see (and connect to) it properly. I've tried resolving it by rebooting the iPhone (iOS 9.1) and resetting the Chromecast device (Firmware 1.16.43955). Both devices are on the same network and, additionally, the Chomecast device has guest mode enabled. I'm running Spotify version 4.4.0.
This used to work. Any ideas?