External Display USB-c Monitor issue

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.

Re post: https://discussions.apple.com/thread/252078217?answerId=254525398022#254525398022

I just received a response from Apple Support:

• DisplayPort adapters are NOT supported and NOT INTENDED to work, even if they were working in 11.1.
• The recommended adapters are: HDMI to DVI, then DVI to USB-C.

I am still trying to find a bi-directional DVI <-> USB-C adapter. Can anyone recommend one?

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.

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

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

jefffffffff wrote: "If Apple engineers, tech support, cust svc don’t read these every day they should all be fired."

Apple reads our direct feedback about macOS at the link below. As the ASC Use Agreement says: "Apple Support Communities is here to help people use Apple products and technologies more effectively."

Feedback - macOS - Apple

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Hi Sfilimonov,

thanks for your suggestion. It doesnt work as the display is not recognised properly. Its recognised as a 60hz 1080p 30" display, while it is a 4k 60hz 27" display..

IMHO, the new Bug Sur 11.1 caused some problems with the communication with the external display(s). As I can see from above, it is a widely popular issue, too.

chadfromiowa, if Bug Sur does not support dual external displays, it should go directly in the trashcan :) It should support dual external displays, but currently, evidently there are bugs in their official release. Hence the new name. Obviously Apple are all over themselves with the positive reaction to M1 and they are rushing to add new features for these issuing half-baked updates, but seem to be forgetting that none of their flagship models are not currently on M1 yet. Neither is any useful software.

Hopefully they will issue a patch soon. I mean the bug is so blatant that it shouldnt be hard to spot and fix.

In the meantime the only workarounds that I found are

1. restart in safe mode (press shift during Apple logo while booting), then restart back to normal. It seems that it 'resets' some stuff and you are able to scale the display back to whatever its full res is.
2. switch the input of the display. So if the bug appears on usb-c to usb-c input, switch to usb-c to display port, hopefully you have more than one graphics cable at your disposal. Alternatively, if you are running on usb-c to display port and the bug appears there, switch back to a cable usb-c to usb-c. The problem with this approach is if the display is calibrated on usbc to usbc :(

hopefully this helps someone..

best,

Nick

Just following up on the above cables that I ordered: they do not work.

From trying various options and solutions, and what Apple engineering and support have relayed to me, the following technologies will NOT work on the HDMI output of Apple M1 Macs:

• any DisplayPort connectors
• any USB-C connectors

It seems the only connectors they support are DVI connectors, per their claims.

To be clear, I do agree that this is a macOS issue, and they should fix the problems people are having. It's clear that these can be fixed if they wanted to, as for my particular case everything was working fine in 11.1. Further, I don't see any solution to my particular circumstance, as there are no DVI-to-Thunderbolt adapters or HDMI-to-Thunderbolt adapters (as I would need to convert my HDMI to DVI, then to Thunderbolt for the Ultrafine 4k displays).

To clarify how I did the second install:

1. I had 11.0 installed. I did not want to upgrade to 11.2.1 to avoid any issues.
2. I turned my MBA M1 off and pressed the power button for a few seconds.
3. There I created another APFS part on my SSD (I am not sure how it's named in English version of macOS) with the Disk Utility.
4. I installed a fresh macOS (on M1 Macs the newest version is always installed) of 11.2.1.
5. I booted my Mac from the new part of the SSD and checked if the issue was still there. It was not present.
6. So I upgraded my main system from 11.0 to 11.2.1 and deleted the test one. Now I have one, the old system, and I did not go through the pain of setting up again as new.

Is there anyone from Apple reading this thread?!

I have a Dell U2719DC 2560x1440 that used to work fine when connected to my Macbook 12" 2015 until I upgraded to MacOS Sur. I use a DELL PC for work which has no issue with the USB-c port...

Pattern connecting:

• Usb-c connection to Dell Monitor with my laptop screen open = [X] Forces 2048 x 1080
• Usb-c connection to Dell Monitor with my laptop screen close = [OK] Dell monitor is 2560x1440!! This just worked as I was typing this line...
• Usb-c to Apple extension port to HMDI - [OK] Dell monitor is 2560x1440 but I lose all the USB features such as having my Dell sound bar connected or using my external usb keyboard.

Hi all,

I have this issue on a MacBook Pro 16, AMD Pro 5300M. It appeared after upgrading to Big Sur 11.1. It didnt not appear under the initial Big Sur update.

I am using a BenQ SW271 4k as an external display over USB-C. When I plug in the display it only shows as a 1080p screen.

looking at the About this Mac -> displays it is shown as a 30,5 inch 1920x1080 display

I find this highly disturbing that Apple would release such an update as I feel my configuration should be a pretty normal one for a creative professional. An industry which Apple should very much be catering to.

I had a brief workaround by restarting the laptop in Safe mode and then back to Normal mode. The screen was recognised as the 4K screen that it is, BUT unplugging it and plugging it back in resulted again in a 1080p screen which is atrocious.

I thought Apple does test its updates, but this unfortunately proves me quite wrong. At the moment my monitor configuration is plain garbage and I am very much prevented from doing my job. Of course being a decision maker in our company on creative platforms, this does ring a very distracting note..

I hope this is actually looked over by someone in Apple with a basic understanding of technology and the matter is resolved today.

thank you

I tried to reset NVRAM (Restart your computer, press and hold CMD+OPTION+R+P until it restarts for the second time). It kind of helped — when my external display was working along with open MacBook's display I saw the good old 4K@60 but when I closed the lid, it became 30 again. Since then this trick doesn't help. But you can try. But it's definitely the OS problem. A HUGE PROBLEM FOR THOSE WHO BUY $2000 LAPTOP TO WORK WITH AN EXTERNAL DISPLAY.

If one need a workaround one can try to connect the display via HDMI, it should work.

I’m experiencing similar issues with my MacBook Pro M1 attached to my LG 27UK850-W. Also my display scaling on the external monitor along with the color profile keep getting screwed up (gets big, and washed out) when waking the MacBook from sleep. Opening and closing the MacBook usually fixes it (or vise versa).