For the last 6 months, I’ve been swearing at the Function [Fn] Volume shortcut keys on my G3 Elitebook not working.
There’s a lot of people on the web with similar issues over the last few years, and both HP and Windows updates have been blamed equally:
https://www.google.com/search?q=Elitebook+function+volume+keys+not+working&rlz=1C1GCEA_enAG745AG745&oq=Elitebook+function+volume+keys+not+working&aqs=chrome..69i57.10995j0j7&sourceid=chrome&ie=UTF-8

There were a bunch of fixes listed on different sites, none of which worked for me. I suspected HP hotkey drivers being incompatible with recent Win 10 build updates after a lot of driver updates recently. So I had kind of given up and was hoping the next Windows update release cycle might fix
Then recently, this new large OSD volume control started appearing:

With it continually getting in the way, I went in search of a fix to disable this new annoyance, and found it here:
https://www.tenforums.com/sound-audio/134123-windows-10-volume-bar-top-left-huge-4.html
Turns out this is a new feature in Chrome enabled by default, and it can be turned off by entering the following flag in the address bar and using the drop-down to disable:
chrome://flags/#hardware-media-key-handling
Lo and behold!

My function volume keys started working again! So I suspect my issue all along was Chrome and this, or previous incarnations of this OSD, tying into my OS in a way I had most certainly not asked it to.