Audio over HDMI via USB-C Dock broke recently - module-alsa-card.c: Failed to find a working profile

[GitHub issues - opened]

alsa-project/alsa-lib issue #112 was opened from asgrim:

Hi folks, not sure if this is related to #104 since I get the same error, but slightly different characteristics. Running Ubuntu 20.04.1 here.

I've got an XPS 17 9700, which is plugged into a Dell WD19TB dock via USB-C. Off that, I have a Dell 34" screen via HDMI, into which my speakers are plugged in. My headphones are plugged directly into the WD19TB dock. I do have a Yeti mic as well, which is plugged via USB into the dock also. I often switch between my speakers/headphones using a Gnome extension (I select either `Headphones (USB Audio)` or HDMI something (can't remember what it was called exactly).  However, I noticed recently (maybe last week or two?) I wasn't able to switch. Looked into it today, it's because the HDMI audio output seems completely missing. Does not show in regular Ubuntu sound settings, nor in `pavucontrol`. Checked /var/log/syslog, and found this `Failed to find a working profile` message.

Some Googling bought me here, hopefully you lovely folks can help!

* `pacmd ls` output is [here](https://gist.github.com/asgrim/1788fcae11cd1d0ced106c5d94199f29#file-pacmd)
* `pulseaudio -vvvvv` output is [here](https://gist.github.com/asgrim/1788fcae11cd1d0ced106c5d94199f29#file-pulse)

Hopefully this is just user error, but this did used to work, and I don't know where to ask for help as I know nothing about Linux audio stuff :D

Side note: I'm aware there's an issue with my XPS 17 "onboard" speakers not working, they've never worked; I believe there's a fix out there, but it looks complicated so I have so far avoided it. I'm ok with this as I've got the external speakers anyway.

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/112
Repository URL: https://github.com/alsa-project/alsa-lib