So all my troubles are because YouTube wouldn't recognize my PC as being HDR enabled under Windows 10. I just upgraded to Windows 11 yesterday and now all my HDR videos on YouTube are showing the HDR logo.
If you switch over to software rendering then that option will stick. The issues seems to be Adobe understanding the various GPUs (and drivers) and what they can and can't do ... anyway, side point, Adobe should simply NOT show the option if the GPU hardware isn't able to support the Max Render Quality option ... allowing users to check this option but ignoring the user input because of hardware acceleration is just going to trigger confusion and more support questions.
I'm not sure what Hardware actually support Max Render Quality but I'm guessing something very expensive and exotic as you definitely do NOT want to be rendering as software as that will take forever and a day pending project and encoder.