Hello Tom M,
I would suspect that you have other applications that may be taking control of the Device. Do you see other options enabled in Advanced Sound settings? In my case I had to Disable "Dolby audio processing" as some chipset app was taking control for Dolby Processing.
Additionally you can run a Clean Boot, to isolate if the issue is Windows or 3rd party apps and which one:
From msconfig.exe go to Services tab, and check "Hide Microsoft Services" then Disable all. Reboot and test. If the headsets works, you can then enable services one by one and reboot to know which one is taking over and engage with their support or their forums.
Last but not least, could be a driver corruption. I would suggest to Uninstall the headset device from "Device Manager", reboot and install again. Maybe download latest drivers.
Hope this helps to resolve your question!