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Some Users Having External Display Connection Issues With macOS Big Sur 11.1 and 11.2

In recent days I have seen something new.

From time to time, my external display turns completely black as if the onboard graphics adapter performed a hard reset on the external display.

And unfortunately, I can only return to 4K resolution when performing a fresh reboot.
 
shutterfreak said:
In recent days I have seen something new.

From time to time, my external display turns completely black as if the onboard graphics adapter performed a hard reset on the external display.

And unfortunately, I can only return to 4K resolution when performing a fresh reboot.
Click to expand...
What worked now, is:
  1. Disconnect the MBP from the external display (unplug USB-C cable)
  2. Put MBP to sleep
  3. Wait a couple seconds, then wake up the MBP
  4. Plug the USB-C cable from the external display back into the MBP
 
Seems then that it's quite finicky based on individual machines. I'm going to see if making the computer never go to sleep prevents the issue from occurring.
 
I think I have it sussed for now.

I spent a while researching the problem today.

I've managed to reduce the ridiculously high CPU utilisation thanks to the WindowServer process by resorting to using the MacBook Pro in clamshell mode. With the external display connected via either USB-C directly or DisplayPort via the Thunderbolt dock, I have theoretically reduced the average utilisation to under 10%.

I now have a 2020 16" MacBook Pro connected to my LG 4K monitor, able to support 2160p at 60Hz refresh rate without bringing the entire system to its knees. That means I've had to ditch using the built-in display on the MacBook, but that's no terrible hardship, as I can use multiple desktops, as well as a far higher resolution display.

It's not a solution to the problem by any means, but it is a more than acceptable workaround.
 
hello!! i was wondering why is quite a few times i can't use any external monitor on my mac...found out that since bigsur 11.1 is out i couldn't connect. mbp 2017 with amd 650...tought 11.3 would resolve my problem...just to let you know i have used 2 different ways attach my mbp, first one is with their adapter (apple's adapter from usb-c to 3 ports hdmi-usb-usb-c) second one is a usb-c to hdmi. at first i tought it was only a power problem since mac started telling me there was not enough power...so i bought another adapter with Power Bank but the problem still there. Frustrated i wondered if something was broken due to a monitor issue i found out my mac has (and it is a common issue to my range of models it appears)...but when i switch to bootcamp then all the cables and adapters are working no problem...all 3 of them...but my problem is still there...resetting all the rams more and more times doesn't make any progress...not even flickering or trying to show something...only in windows they are working...so for sure is a bigsur problem...what i am afraid is that since is a mac from 2017 they will ignore it and just take care of 2020+ models and m1 chips...but right now with covid and all i can't affort any of their new macs...is there any way to know why in bigsur doesn't even trigger a glitch on my monitor? new firmwares? something? we have to wait now for 11.4 that will fix this and that but what about a simple monitor which supports 1920*1080 hd? It always worked and now i can use it only on windows?
 
sirozha said:
Thats an understatement. Huge issues with external display for me on the M1 MacBook Air. HDMI connection is not recognized after the Mac goes to sleep. I have to unplug the cable and plug it back in and then bang on the space bar repeatedly for the Mac to detect the monitor via the HDMI port on the monitor.

The DP 1.4 (5K) connection on this monitor is not recognized by the M1 MacBook Air at all no matter what I do. It works just fine with the 2020 MacBook Pro (10th generation Intel CPU).

Apple admitted to me (after a month of me badgering them and demanding that the ticket be sent to Engineering again and again) that the M1 Macs have an issue with DP1.4 not being recognized.
Click to expand...
Thanks so much for mentioning banging on the space bar. For some reason, my Cinema Display and my 17" MacBook Pro (using UpTab's adapter) weren't playing well together after I updated to macOS Big Sur 11.3.1. I thought the monitor had died and then I tried the space bar. Everything is happy now.
 
MacBook Pro (16-inch, 2019)
BenQ PD3220U connected with thunderbolt 3 cable.

Waited until 11.3.1 was out to upgrade and have no issues.
 
I've noticed that my screen often cuts off when I put my phone near or on my computer. I don't know if this is the *only* problem but I just put my phone on a wireless charger next to the computer and it immediately shut off, and that's happened before. There's another time where I just put the phone on top of the computer. iPhoneX.
 
Recognizing devices on the external monitor is also a problem.

My 16" MacBook Pro (Intel) with two Apple monitors:

  • Does not see an Apple keyboard connected via the USB ports on the back of the monitors
  • Does not display the microphone built into the monitors as an option in the Sound Control Panel
  • Does not display the speakers built into the monitors as an option in the Sound Control Panel
Reboot or unplug/plug cycles do not fix the situation. But a sleep cycle did. Go figure. Hope this "fix" holds.

Update: Alas, the fix went away fairly fast when I had to reboot for other reasons. Sigh.
 
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cjamescook said:
Recognizing devices on the external monitor is also a problem.

My 16" MacBook Pro (Intel) with two Apple monitors:

  • Does not see an Apple keyboard connected via the USB ports on the back of the monitors
  • Does not display the microphone built into the monitors as an option in the Sound Control Panel
  • Does not display the speakers built into the monitors as an option in the Sound Control Panel
Reboot or unplug/plug cycles do not fix the situation. But a sleep cycle did. Go figure. Hope this "fix" holds.
Click to expand...
Try a more powerful power brick. I’ve had similar problems and noticed recently when I charge my phone off the same brick the monitor and keyboard cut our.
 
iMac (Retina 5K, 27-inch, 2019) - My old Apple cinema display (thunderbolt) has ceased working as well. If I unplug and plug back in or restart the computer eventually through some random acts it'll come to life. Typically these OS updates don't ruin my life quite like this one. I've had other compatibility issues that have halted all work.
 
Still can't get my Cinema Display working. Is there no fix in sight for this problem? It's been 6 months with these problems now. Have they no clue on how to fix this?! :mad:
 
I just upgraded to Big Sur on my 2019 MBP as I had other concerns. I hit the external monitor problem immediately. Now I have a BenQ and a Dell U3219Q hooked up, daisy chained through the BenQ. The BenQ provides power through the T3 connector. The daisy chain is via USB-C from BenQ to Dell.

This worked on Catalina mostly flawlessly, although at times I would have to change Tbolt ports on the mac when waking from sleep and the monitors weren't recognized (annoying, but simple procedure - 1 cable unplug, plug into other port, all good)

After upgrade to Big Sur 11.4 - neither monitor was recognized, and no plugging into left vs right ports on MBP made a difference. Then I unplugged the Dell from the BenQ, and the BenQ was recognized, plugged the Dell directly into MBP, it was recognized. So now we'll see if they'll work flawlessly, although it's a bit more of a pain to have 2 cables vs 1. :(
 
Apple clearly don't give a rat's proverbial. This much is clear.

The only reasons for any of the tech giants to fix anything they break, these days, is if enough people open support cases about it, to register a blip on their bottom line or if a class action is possible.
 
This is still an issue for my wife's M1 iMac. The second LG monitor, plugged in via DP to USB C, keeps waking every few minutes and says that it's going to sleep.

This was not an issue with a 27" iMac 2015.

It is updated to macOS 11.5.
 
MM07 said:
This is still an issue for my wife's M1 iMac. The second LG monitor, plugged in via DP to USB C, keeps waking every few minutes and says that it's going to sleep.

This was not an issue with a 27" iMac 2015.

It is updated to macOS 11.5.
Click to expand...
I've had odd issues with versions going back to yosemite on screens sleeping (the first version I noticed problems with dual monitors) I had the other problem - they went to sleep without me wanting them to. Caffeinated fixed that problem, but won't address the one you have. Since I went with the dual plugins, I have not had any further issues. A friend of mine has dual LGs connected via daisy chain, and he has no issues either (but note they are same maker, even if different monitor lines - 5K and 4K)

You could have something running in the background that's causing that issue. Screen sharing definitely does strange things if it thinks anything is connected even when it's not. I have a 10.13 system that is mostly connected to via screen sharing, and it does odd screen blips on its sometimes connected monitor. That system had issues with this all the way back to 10.10 as well that I know of, because that's when it became a secondary.
 
Same. 2020 iMac recognizes the external (Samsung) monitor using HDMI and an adapter, but not with USB C/TBolt to DisplayPort cable.
 
I'm having this problem on my M1 MBP 13" and it's gotten worse, to the point I can't even get my BenQ SW321c to connect at all anymore. It's maddening, as I need this to feed my family as pro photographer. It was happening on 11.4 and it's still happening on 11.5.1!!!

Has anyone had any success???
 
I've got a 2016 map 13 and my USB-C to DisplayPort cable that used to work no longer works. I don't know since when it was broken but I have 2 identical monitors with the same cable and it is not being detected at all. Unfortunately I got no other cables I could test easily as I am currently in lockdown here. (I do know that it definitely never worked since I upgraded to BigSur) I have tried doing a pram and smc reset, and also tried to use the detect display and manually change the resolution scaling and it doesn't appear to do anything.....

If someone do know of a solution please do help.... many thanks.
 
Adding myself to the list of people experiencing the issue.

I have a Dell U2422HE with a 16" MacBook Pro. When I first got the monitor it didn't work but after a bunch of restarts and unplugging and plugging it back it a few times it worked. Every now and again it would stop working but I could get it working with a few restarts or reconnections, but after 11.5.2 it just doesn't work at all anymore. Charging and USB is working fine, it's just video that's not working. Extremely frustrating.

I recently had an M1 MacBook Air that I was setting up for a friend and I had no issues with connecting that.

I'm thinking of trying the Monterey public beta as a last resort. Has anyone tried that?

UPDATE: So I found something that seemed to work for me. The monitor in question has a DisplayPort input, and when I connected to that input using a USB-C to DisplayPort cable, while still connected via USB-C, it seemed to "wake up" the USB-C port, and video started properly being send over that cable. I was then able to disconnect the DisplayPort cable and the USB-C cable continued to work.
 
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