There was a time where "Chromecast Built-in" devices wouldn't work with Audio Groups. But, they should have all been updated by their manufacturer.
I would suggest contacting the company that made your TV and make sure they applied the appropriate updates.
I'm also wondering about your version of Chromecast. I believe 1.50 is only available on Chromecast Ultra devices. All others are still on 1.49 or earlier
Just wanted to jump in here to check to make sure that you saw the response from Byteguy. Shoutout and huge thank you to Byteguy for the help here. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.
Have a great day.
It looks like we haven't heard back from the OP so I'm going to go ahead and lock the thread. If you have any further questions or concerns, feel free to create a new thread.
Have a great day,