According to the home app, the Google tv cast version is 1.56.292394 I
can cast from the YTM app and the home app to the TV only, and in the
home app I can select all the individual devices that are a part of my
speaker group, but selecting the speak...
Removing the Google tv I added to the speaker group immediately resolved
the issue. With the Google tv in the speaker group it says "YouTube
isn't installed at the moment"