External Monitor Resolution Refresh in Big Sur

Had the same problem with my LG 4k screen. What I did was set both the monitor and built-in retina display to default resolution. Then I turned off the monitor. After that, both screens were running 60hz, then I chose again the scaled option for the monitor, and it's now running at 60hz. Hope this helps.

My solution was to downgrade to Catalina.

Honestly, after staying on Big Sur for a month, I found Catalina such a better OS when it comes to UI.

Same problem with my MBP 16 and a 4k Benq SW271. Had to downgrade to Catalina. Shame for Apple. Have a question for them: do you know there's still some pro are still using your product?Do you want to loose all pros? If yes you are doing it right!

I have the same issue. How do you guys go about having this issue for so many months after the update. Atrocious from apple. The UI seems like a step backward to the early 2000s and most of my music VSTs are broken

Same issue here with LG 4k; after update to Big Sur only 4k@30hz.

I use SwitchResX but this tool also no longer shows 60hz resolutions.

Same here, so frustrating

After some fiddling and trying things I got it fixed. The fix was to no longer use the displayport cable (that worked before) and switch to a high quality HDMI cable....