HDR option not available for external display

OK, if I set my refresh rate to 30hz, the HDR button reappears. I'm still finding myself saying WTH Apple. My imac Radeon 5700XT can handle much higher refresh rates.

Cables need to support the bandwidth required for both HDR/Dolby Vision and refresh rates. As we should all know by now not all USB-C cables are the same. This is where I suspect the problem lies.

And as a general rule of thumb never assume a third party display will be completely compatible with Apple hardware. Always search and investigate before buying.

I don't think you did anything wrong. I also have the Asus ProArt PA279CRV as an external monitor, on an iMac2020 20.2 with the Radeon 5700XT video card. I've tried everything here as well. also tried it at 1920 x 1080 resolution. I tried displayport, USB-c to displayport with adapter, and a Thunderbolt3 cable direct from mac to monitor. I'm not seeing the option for HDR in the displays menu, -I still see it on some other machines running Sonoma 14.5- The PA279 supports HDR10 What gives apple?

Then there is no answer for you except to return the monitor and try something else.

I would like to work in 60hz at least.

once I found this 30hz issue, I did find it mentioned in other places. it seems gamers aren't happy.

I also think ASUS owes it's users firmware that doesn't make you jump through so many hoops to get that monitor hooked up to a mac. The procedure, in order to get DisplayPort 1.2 turned on and thus connect to my imac was foolish. So many hoops. although once the monitor was connected at 1.2, I can now set that monitor to Displayport 1.4.

I wish you were correct Ikrupp, but I'm running correct and tested cables on my system.

BTW I'd be embarrased to post if I hadn't done those basic troubleshooting steps. but thanks for the technical and consumer tips.

ASUS sales research and general reviews all indicate that it's compatible and it absolutely fits the spec for my Apple machine.

It's just not the kind of problem you can really search for until it's a problem. It definately seems to be in the underlying software.

The spec for my iMac

• Two 3840-by-2160 (4K UHD) external displays at 60Hz with support for 1 billion colors, or
• Two 4096‑by‑2304 (4K) external displays at 60Hz with support for millions of colors
• Thunderbolt 3 digital video output
• Native DisplayPort output over USB‑C