Very aggravating. I’m sure the answers out there. Googling is tricky sometimes. The answer might be the 50th google response that I never make it to, because I gave up. Another person with the exact same problem could post the same question in a slightly different way and the very 1st hit could solve the problem.
Do I query about “no HDMI audio on the HP EliteDesk 800 G5 Mini” or “Mate doesn’t show a HDMI device option”. Or you see something interesting then realize it a Windows solution even though you specifically specified Linux. Then you look at a promising response and realize the response is from many years ago and doesn’t apply to Mate today.