DP-HDMI no audio, Ubuntu 18.04

Intel HD graphics 4600/Ubuntu 18.04/MythTV 29.1
My SIIG DP to HDMI adapter works, but it only supports 1080P. so I know the PC, cable and TV are all fine. the only thing that changed is the DP adapter.
4k video output = works
audio output = does not work

steps taken:
Correct DP/HDMI port is selected in Ubuntu Sound Control
In MythTV frontend-setup-audio, the HDMI dev=0 is detected and my LG TV shows up
Searched the pluggable forum, but only a few comments from Windows users

please advise

Hi Daran,

Thanks for reaching out to us, I am sorry this is not working as expected.

The audio settings should be the same inside the operating system for both adapters.

Our first step is to check if the audio pass through is working in the DisplayPort to HDMI adapter, we can reduce the resolution to 1920x1080, save the resolution and restart the computer. When the system has loaded back up please test the audio output through the adapter to the display.

Please let me know if audio pass through works at lower resolutions and we can go from there.

Thank you,

Pat
Plugable Technology

Hello Daran,

We’re closing this thread due to inactivity, but if you have any further questions please feel free to contact support@plugable.com and we’ll be happy to help.

Thanks,

Pat
Plugable Technologies