My MacBook Pro 16 2019 has automatically upgraded to Big Sur 11.1 beta and forced my external display LG27UL550 (mini-DisplayPort) to run 4K in 30hz. How to fix this or downgrade to the stable 11.01 release?
MacBook Pro 16″, macOS 11.1
I — the topic starter — have long waited for the fix to come and saw no progress in this discussion for my case. So I wrote to the chat of Apple Support and gave them the link to this discussion, then a specialist called me and calmly said that to prove that this issue exists I personally have to have macOS 11.2.1 installed (I had 11.0 as I was afraid that upgrading to 11.2.1 will return the issue to my computed) and confirm that the issue still exists. So he recommended me to install another macOS system on another part of my SSD. I did this — and THE ISSUE IS GONE. I have MBA M1, LG27UL650 connected via USB-C-to-mini-DisplayPort cable. My issue was that the display wouldn't work with my old MBP 16 2019 in 4K@60hz mode, only 4K@30Hz or FullHD@60hz after upgrading to 11.1.
Under 'display' in 'About this mac' my BenQ PD2700U is showing as a 61-inch monitor ha! This is so bad.
Big Sur 11.1 beta forces external 4K display refresh rate to 30hz
