Thanks for the suggestion. I can confirm Audio is enabled in the Bios.
What should happen when you plug something into the front jack?.......does it disable HDMI sound automatically?
My Windows 'Sound' window only shows my monitor in it......Acer 23" T232HL LED IPS Touch Screen: actually, this only appeared after the Bios update: previously it just said " Digital Audio (HDMI) High Definition Audio Device Default Device".
So the fact that you have 3 pole headphones working in your NUC, suggests to me that my front panel jack is faulty.
Would you agree?