I'm starting to think this is a software issue/bug with AMD's drivers rather than a hardware issue. The reason I've ruled out it being hardware is because when I turn GPU scaling to OFF, I can select the 75hz refresh rate in my Windows 10 display options. The 75hz is verified through in-game FPS counter. When GPU scaling ON, it instantly reverts back to 60hz, and the 75hz option no longer displays in the drop-down selection box.
Based on this information, would everyone agree it's a software issue rather than hardware? Anybody else encountered this problem? I really would like to use my monitor to its full capacity. The monitor is an Asus VG245H connected through HDMI to an AMD RX480.
I don't believe it's a specific driver version issue. I have been having this problem with ALL versions of the driver, old and new - from the very latest driver all the way to the drivers before the ReLive rebrand.