Big Sur 11.1 External Display Issues!

System Preferences > Displays > Hold Option key on Keyboard > Detect Display

This might work. I had the same issue and this was the solution.

I think this really depends on the make and model of your display. I'm using a fairly new display that has direct usb-c to usb-c capability. Within the settings on the display's OSD I am able to select which version of the display port it uses. My options are 1.4, 1.2, or 1.1. Factory default is 1.4. This is the version that allows for HDR and what I was using prior to Big Sur 11.1 with no problems whatsoever. Immediately after installing the 11.1 update the display wasn't recognized properly and the OS showed it's maximum native resolution to be 1080p and sometimes 800x600 depending on what sequence I plugged and unplugged the connection. The only way I got it back to 4k was by changing that setting directly within the monitor OSD. However, as I mentioned the OS is still incorrectly identifying the make and model of the display.

Using a different connection than USB-C fixed the problem for me. I'm running a 42" 4K LG display via an Elgato Docking Station with DisplayPort now, which works as expected. Connecting the same display to the USB-C port on said Elgato Docking Station does not recognize the screen at all.

Same issue. 16MBP from 2020, BENQ EW3270U 4k monitor connected over usb-c/thunderbolt to DP cable by belkin.

Prior to 11.1 update everything was working honkey dory at 4k native resolution, HDR and 60hz worked fine.

After it - didnt wake up properly. couldnt detect monitor correctly, couldnt detect resolutions properly. Couldnt detect refresh rate correctly. Good job! /s

Reading here - it seems it plagues DP connection. So now, I went and got a Thunderbolt to 60hz HDMI adapter by Satechi. Plugged it in, and laptop woke up, detected res properly et cetera. It does seem I have lost the HDR detection, but I can live with that - I wasnt really using that in the first place.

I also have the BenQ PD3220U..

I managed to fix this from going into the Monitor Settings and switching the Display Port off 1.4 and Selecting 1.2, I now see the original OSX scale options..

Difficult to believe this is an issue.

I got 60Hz back. I purchased a HDMi(4K)-USBC (https://www.amazon.de/gp/product/B077FGWN3M/) and connected my MBP16" to my BenQ PD2700U. At first still no 60Hz option in the Big Sur Settings so I downloaded Display Menu (https://apps.apple.com/us/app/display-menu/id549083868?mt=12) and with that my option of 60Hz and all Res were back. This only worked for the HDMI connection - the USBC-DisplayPort is still not showing 60Hz in the Display Menu. Oh and DisplayPort Setting of the BenQ has to be 1.1 to at least get 30Hz at HighRes - 1.2 only gives 1080p (ggggrrrrrrr)

The more of us reporting it, the bigger the pressure to have a solution.

I started bugging @AppleSupport on Twitter and it worked as they replied and got interested in my case.

Apple don’t read these forums but they are open to help when they get a call. I was on the phone for more than a hour with Apple Support from Sydney a couple of days ago. After PRAM reset, deactivating HDR and TrueTone and SMC reset and other tricks, at least the two external LG monitors work at native resolution (4K & FHD) with decent colours with my MBP16. I’ve been said Apple knows the issue and a fix will come soon.

I am experiencing the same issues. Very frustrating.

The workaround I've found is using my (active) TB3 <-> HDMI cable. This leads me to believe the issue is related to the Displayport profiles.

Really wish Apple would get on fixing this.

I was experiencing issues with my 4k 60hz Samsung monitor- terrible UI lag and videos were laggy. connected via a J5 create usb c to HDMI cable. this is how I fixed the issue; Click option while selecting scaling in the display menu and a longer list of resolutions should appear. select lower resolution and choose the same resolution you prefer, but in "low resolution" version. this does not degrade picture quality at all I find and brought performance back to smooth and normal.

Hi folks!

Same problem (27” Benq monitor with USB-C) but try this old app from App Store - Display Menu. It works, including 60 Hz refresh rate for 4K res monitors.

Until someone from Apple fix it this let you work.

Oh thank goodness it's not just me. I've been suffering this exact problem, reformatted on the weekend thinking something must have been corrupted and was furious to find it's still completely broken on 11.1. The display has never caused a problem through Mojave, Catalina and 11.0, but 11.1 has really screwed something. There's no consistency in when it detects it correctly and when it doesn't. SMC/PRAM resets don't fix it. Occasionally it'll detect it perfectly, and then plugging in/out another display will bork and and suddenly it thinks it's a 1080p or 1600x900 or 1280x720 max resolution screen.

Based on a comment here I dropped the displayport version in the monitor OSD and it looks like it's detected it correctly, but I have zero faith it's not just a coincidence and will screw up again next time I have to restart.

Apple, please for the love of all things good, do something about your software quality. This is rubbish and you've been on a steady downward trajectory since Snow Leopard.

As for new hardware you are right. Everything worked great before the 11.1 update so there is no reason to buy something new. BUT the software is different case.

If the system (through the bug) hides optimal resolutions with relevant frequency, there is no question to use 3rd party product that enables what the system cannnot. I am using Display Menu App since the problem occurred and I am absolutely satisfied with it. The price is extremely low for what it can do.

Yes, sometimes you have to combine it with some annoying things – turning on and off the monitor or unplugging the USB-C connector from your MacBook Pro but it works!

I am a big dreamer. But waiting for the salvation from Apple is pointless. Sorry.

(sorry for my english)

I have the same issue now on my 16" MBP with a BenQ PD2720U monitor. Everything went wrong once I updated and then reconnected the laptop to the screen. My work 13" MBP with Catalina has absolutely no issues.

Thanks to everyone that suggested switching in the monitor menu "System - Advanced - DisplayPort - 1.4 to 1.2", this fixed the issue for now, but only when I connect with the Thunderbolt 3 cable. HDMI (both Apple display adapter and a USB-C hub) is still messed up showing a full 4K non scaled resolution.

I had several problems with Big Sur at the start: Bluetooth mouse kept disconnecting/connecting at regular intervals; monitor not connecting via USB-C cable. Since 11.2.1 the issue with the mouse disappeared, now it looks like (at least for me) also the one with the monitor disappeared.

I still seem to have some issues with running some software installed cia HomeBrew (e.g. emacs), but I’m not sure if it is related to the OS or XQuartz...

This fixed my "No Signal/No external display detected" issue.

It's a setting of your monitor. For my Dell 4K, it requires press and hold on one of the physical buttons on the monitor. You can check with your monitor user's manual. 

Here is a link to my earlier post.

https://discussions.apple.com/thread/252174979?answerId=254843026022#254843026022