So after a lot of trial and error, I found a way to force HDR on, though it pretty much defies all logic.
First, I have to connect a second, non-HDR monitor up to my PC. Then I set them up as one extended desktop. When I apply that setting, when the image comes back, it's displaying in HDR. As...
For ages now I had a very strange issue, where my taskbar appears completely blank whenever I first turn on my PC. Restarting Windows Explorer, which should usually help, doesn't actually fix the issue. Instead what I have to do is first turn of AppX Deployment Service, then restart Windows...
No, I'm not using any adpters and yes drivers are up-to-date. It's been happening for over a month now so I've gone through several graphical drivers that haven't fixed the issue.
All of a sudden I can't enable HDR in Windows. The second I click "Use HDR", the button just goes from being on to instantly off. Seems to be a Windows-side issue as on the monitor everything is set up correctly to allow for HDR. Even before if HDR was turned off on the monitor it still allowed...