Go to your Google home app, and under "media" you should be able to play
your groups and other devices, or if you are already playing something
you can add devices from the "media" in your Google home app.
I have done that as well and still won't show group as an option when
trying to cast to all speakers, it will allow me to choose what speaker
individually but no group.
Yeah I'm having the same issue and I am having a party tomorrow but
can't even get the group to show up on the list of cast options, I've
reset them all but no luck.
