I have roku express, updated to 9.4. All my channels have audio except hbomax, so my roku is not the problem. To troubleshoot I removed the channel and restarted the roku then added hbomax again. I’ve done this several times without success. The hbomax app works just fine on my iPad, no issues, and it works fine on my desktop. Anyone have a solution to this problem?
Found the solution for my situation. On the Roku, went into settings, then audio and then selected "stereo". This was originally set to "auto". Now HBOmax and all the other channels has audio coming thru the Vizio soundbar.