This is known and is intentional according to Apple. From their reply to Feedback reports:
Hello. Unfortunately, there is a frontend bandwidth limitation that prevents us from reliably supporting HDR at high refresh rates beyond a certain screen size, so we have had to gate the feature slightly more conservatively than in earlier builds of the OS.
Thank you for your feedback.
This is apparently only an issue with M1 Macs. From their reply, it looks to be a bandwidth issue and from people’s research online, the current workarounds are:
- If you are running at 1440p mode like most people with a 4k display, this ironically internally renders at a much higher resolution than the 4k setting. Reducing resolution (Right click the resolution selection thumbnails, choose “show List”, then toggle “Show all resolutions” will give you a list of resolutions beyond the thumbnails), to 2304x1296 or lower, depending on point #2 brings the HDR toggle back).
- The other alternative is to reduce refresh rate. People seem to have noticed the issue only at 120Hz or 144Hz (which again lines up with Apple’s reply of it being a bandwidth issue).
You might have to do mix and match #1 and #2 with different settings to see which gets you under the bandwidth cutoff just enough to let you enable HDR. It working fine on Monterey and Ventura was unintended all along, and was apparently causing issues which led to Apple disabling it on Sonoma 14.1. The final alternative is to downgrade to Ventura, if it’s critical to your work.
My personal M1 Mac is still on Monterey which works fine but my work Mac didn’t support HDR for some reason which led me down this rabbit hole. I’m super disappointed to say the least.
