Symptoms / Issues
Audio setting is stuck on “Dummy Output”
NUC is not playing audio via HDMI
Assumption:
No issue with your hardware.
Sound is working USB-C or 3.5mm jack
Findings:
It appears that the issue is related to the Kernel and the Audio Driver.
Solution:
Updated the Linux kernel from the stock ubuntu 20.04 and 21.04 kernel 5.11.x-xx-generic to the version 5.14.9 fix the issue for us.
Here is the kernel that works for us:
Our new kernels were downloaded from the following URL:
https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.14.9/amd64/
Use
sudo dpkg -i linux[exact version number].deb
to install your new kernel.
Do a google search to find information on how to update your Ubuntu 20.04 or 21.04 kernel.
Update your kernel to 5.14:
NB: Updating your kernel will update your boot files, please make sure that you know what you are doing and that you can recover your system in case the latter becomes unbootable.