I have a Google Chromecast with Google TV hooked to my TV. I have added it via the Android TV remote and via the Google Cast integrations. I can play/pause/change destinations perfectly. When it comes to any volume (volume up, down, mute), it simply ignores me. Even in the states area, it always shows “is_volume_muted: false” which is not true–I have it muted right now. I have restarted HA, the whole TV system, the Chromecast with no luck. It just ignores the volume of this device alltogether.
I’m about to give up here.