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
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