None of those things worked for me. I even edited the file mentioned here.
(If I want to use the audio output from HDMI0, I can see that it is card 0 and device 3. So, to make audio work on my setup, I need to edit the /userdata/system/.asoundrc file and replace pcm “hw:0,0” with pcm “hw:0,3”, and then save and on reboot, it worked. This method might not work in 100% cases, but it’s worth a try.
Worst case, if it doesn’t work and you want to go back to the original state, just remove the file /userdata/system/.asoundrc (or \system.asoundrc from the network share).)
It somehow worked when I updated to the beta version currently out.
If all else fails I would recommend updating the version and then retrying each HDMI output until you find it.