External monitor not displaying in HDR on my MacBook Pro

MacBook Pro (16-inch, 2019)

macOS Big Sur 11.0.1

AMD Radeon Pro 5300M 4 GB

ASUS ProArt PA32UC external display connected via a Thunderbolt 3 cable

I see the "High Dynamic Range" option in the "Displays" preferences on my MacBook Pro, but I don't have it selected because if I do, I'm not able to change any of the display settings on my ASUS monitor.

When I go to YouTube on Chrome or Safari on the ASUS and play HDR content, it doesn't show up as HDR.

But if I play it on my MacBook Pro's screen, it displays in HDR.

I also tried selecting "High Dynamic Range" and same result. Am I missing something?