When trying to group zones the option to Group Zones in the top right hand corner of the zones acreen is greyed out and unselectable.
I have 3 Chromecast Audio zones that I want to group but am unable to do so.
Is grouping supported with Chromecast?
That I am not sure. I just know you have to group them in Google home. I think Google home will look after the sync if you play to one of them. But I could be wrong.