After upgrading to ubuntu 20.04 the hdmi sound stopped working. If I select headphones as audio output they work well, but if I change to HDMI output it doesn’t work.
I did this and it solved the problem:
rm -r ~/.config/pulse/ reboot
If I would have read further, I could have resolved it without needing to reboot:
killall pulseaudio; rm -rf ~/.config/pulse/* ; rm -rf ~/.pulse*