Only HBOMax app doesn't play sounds out of the sound system.

I have a Hisense l9g Android TV and every app works when it is on tv speakers. I purchase a Platin Monaco sound system for 5.1 movies but when I switch to EARC, every app EXCEPT HBOMax plays sound. It's very odd and peculiar. I uninstalled the app and restarted the TV before reinstalling it but still, no sound. I have to switch back to the TV speakers for HBOMax content. Anyone else seen this? I was so hyped to hear Godzilla vs King Kong.