Due to the thread bump I decided to dig out my machine that has this issue. I tried fresh installs using the latest 11.0.6 and the 12 nightly.
The no audio over hdmi still persists.
Audio does work through spdif and the headphone jack.
For those that are interested, here are the debug logs for posterity
I did try some different linux live distros in the past with mixed results trying to determine the no audio over hdmi issues. From what I remember the Ubuntu one had the same audio issue while a distro like Linux Mint 21.1 had audio working out of the box.