External Display USB-c Monitor issue

Don't give up. It can be fixed it took me a really long time. USBC to DP was important for me also be patient sometimes in takes 15 - 30 seconds for my M1 to realize there's an external monitor and wake it up.

After fighting with this crap on a 16" MacBook Pro and an M1 air the ONLY reliable 100% way that I found (for me) was USBC to DP. I am finally happy at least with this part now.

I think my issue is connected to this https://discussions.apple.com/thread/252078295

It might feel choppy because Big Sur forces your external display to run in 30hz instead of 60hz. I've had betas of Big Sur with my MBP16 and LG27UL550 and all worked normally. This is SOOOO frustrating! It feels like your computer for $2000 started to work 2 times slower.

Have any of you folks tried resetting PRAM yet? I did that this morning and also deleted this file before rebooting:

~/Library/Preferences/ByHost/com.apple.windowserver.[UUID].plist

...since then I haven't been having any weird issues with my 4k display over DisplayPort. I did give up on USB-C though. It was still crashing my machine before this change this morning.

https://support.apple.com/en-gb/HT204063

Hey not sure if this helps at all but I have an LGHDR 4K ultra fine monitor that I use as an external with the 13” mbp. I had the EXACT same issue (pink flash and all) when I used the thunderbolt port on the monitor, if I switched and went to just plain ol USB-C it worked competent fine, no crashing at all and still charges the MacBook (not as fast but it works). The only issue I have still is trying to wake the external display. It’s 50/50 if unplugging and replugging will work, if that doesn’t then I need to restart. Pain in the *** either way but definitely better since I stopped using thunderbolt 3.

I just got my new Macbook Air M1 with Big Sur 11.0.1, and connect usb-c to usb-c of LG 49WL95C-W. I used my Apple usb-c cables, I can't get the connection to LG monitor. After I used the original USB-C cable coming with LG monitor, the connection is ok, and ONLY on the top usb-c port of the left on Macbook Air M1. Not working with the second port of usb-c.

In summary, the USB-C port of Macbook Air M1 and the USB-C cable all come to play. The lesson is use the 1st usb-c port, and use manufacturer's USB-C cable.

Hopefully, my experience will help some of your situation.

I believe there's no software solution yet. We need to wait for Big Sur 11.2.

You either get lucky and your screen miraculously works (if it does, don't close your MBP lid or don't put it to sleep), or you wait for the patch.

Apple is aware of the issue and is working on fixing it, but it appears it isn't as simple as we would all like. I've heard 11.2. beta was released in order to test if 'external monitor issue' is resolved, and users still reported the same problem.

I — as one of the topic starters — 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.

Hi guys, I can also confirm that after a week of upgrading my MacBook Pro 16" to 11.3, the 4k issues that I was having have been resolved. Everything seems to be working fine! It took some time, but seems we are there at the end!

I am using a usb-c to usb-c connection on a BenQ SW271 4k display.

11.2.1 is out, have anyone tried it?

I just got done installing 11.3 on my M1 MBP. Thus far all of my issues appear to have been resolved. Fingers crossed that it stays this way!

I strongly believe that you should report this to the Apple support. I can't do this as my Mac is off support warranty and I have a beta Big Sur 11.1. It's better you send them the link to this discussion so that they could see that you're not alone.

I had this problem this morning with my new Mac Pro.

I solved like this.

Clicked on the Apple>Displays>Option+Click on Scaled under the list of resolutions tick on "show low resolution modes" and click the desired size, under Rotation a new drop down menu appears "Refresh Rate" this will give you the option to pick 60 Hertz or 30 Hertz.

I hope this helps you or somebody, I was almost going to return my Mac Pro or return my new Monitors.

Good luck!

I've recently upgraded my MBP16 to BigSur. I skipped the 11.0. version and went directly to 11.1. but I still experienced the issue mentioned in this thread. Specifically I have a LG UHD 32 monitor connected via USB-C cable. When it wakes up from sleep the resolution is on 720p.

I found a solution on developer.apple.com forum which helped me. I hope it works for you as well.

System Preferences -> Display -> Color -> Calibrate... -> Click through all the dialogs