macOS Big Sur - Multiple Display "Recovery"

I have a MacBook Pro (16-inch, 2019) and after the update to Big Sur external monitor no longer works, restarted macbook and unplugged and plugged monitor but the issue persists. I have another Macbook pro 2016 and it works just fine with same monitor but I still have Catalina on it, so pretty sure now Big Sur is the culprit.

Crazy this issue has persisted four months...

I'm on a 2018 Mini with one LG 5k thunderbolt monitor, and one generic 4k HDMI-connected monitor. After upgrading to Big Sur, every window that used to restore onto the hdmi monitor is either half off the screen, or completely off as if the desktop were double or triple the width of the actual display. It happens every time my displays sleep throughout the day, so I have to move all my windows back every time I take a break from work.

Same problem. My external monitor simply refuses to even acknowledge the presence of my monitor. WTH Apple!? I paid a couple thousand dollars for this crap???

I have this issue as well, but with a permanently connected Dell 4K monitor and waking from display sleep. The second low res monitor is fine. Every time I log in, the Dell windows move to the laptop display. This was a problem I solved in Catalina simply by waiting until the monitor powered up from display sleep. Now with Big Sur, nothing I can do will stop it.
It is a real pain, as the whole point of the Dell monitor (used vertically) is that I can have multiple large windows.
(Macbook Pro 16" 2019)

Mac mini M1, BenQ 4k on USB-C and Dell 2k on HDMI (rotated 90 deg.). Scaling is 2nd. highest.

Quite often the scaling on the 4k monitor is automatically lowered to 2nd. lowest, but without scaling the display itself. This means I only see a part of the desktop, and I'm not able to get the Dock or anything else. Most often the 2k display stays a selected scaling, so I can access the dock from here and launch SysPref / Display. I then have to set scaling to highest, and then lower it to my choice of the 2nd highest.
If I'm unlucky that scaling is also messed up on the 2k screen I have to restart the Mac.
Really annoying as it happens quite often.

I have the similar problem.

My external 4k monitor sometimes re-connected with empty screen. Had to pull the app to built-in monitor from Mission Control then move back to my external monitor. (MacbookPro 13' 2017)

Similar Problem.

My external Monitor stopped working after upgrading to BIG SUR on my iMac 2020.

Hi all,
Short Answer
Resetting NVRAM solved the issue for me - https://support.apple.com/en-us/HT204063

Hope it works for you, even though I saw a note here saying it didn't work for one person. It's super annoying if you're used to twin displays.

I'm not a developer, but I came here searching for answers why macOS Big Sur 11.0.1 broke my HDMI to my Panasonic TV (Apple Thunderbolt Display always worked). Would not even detect that I had the TV screen. It was working fine with Big Sur 11.0.0, but I don't know when the autoupdate to 11.0.1 happened.

What Didn't Work
Rebooting several times
Connecting/reconnecting HDMI cable at Mac mini/TV end
Changing HDMI cable
Connecting/Reconnecting to different HDMI port on TV
Plugging HDMI lead into a separate Thunderbolt 3 port adapter and rebooting
Resetting SMC (remove Mac mini power cable for 15 seconds) - https://support.apple.com/en-us/HT201295

My Setup Details
Mac mini 2018 3Ghz 6-core intel core i5
2017 Panasonic TV TH-43D330M 1080p @60Hz
27 inch Apple Thunderbolt Display - connected via Thunderbolt 3 port adapter
Run system as dual display

I’m a autism teacher and have macair with J5 docking station and 2 external monitors for a total of 3 displays. Updated and lost everything, no Ethernet, only one external display and loss of dock station. I had to move everything to external HD and then take to apple to wipe the machine to go back to Mohave. Now everything working. So stupid to release this garbage.

27" iMac with LG 4K secondary display (USB-C). BigSur 11.0.1

After overnight display/system sleep, secondary display desktop "sometimes" comes up displaying only the default Big Sur graphic. No windows. Yet the windows (Safari, Terminal, Finder, etc.) exist - ie, I find them listed under the appropriate application Window menu. In some cases, where windows were on the main screen (iMac), they exist and are visible. Those that are missing had been present on the LG secondary display. Selecting such a window in the Window menu, only brings up the windows that are on the iMac (ie, windows that were originally displayed there). Terminal windows were missing but not all.

Finder was missing 6 of 8 windows. Moreover, safari only shows 1 of 2 windows that were visible when the system went to sleep. Console.app main window not found anywhere - but Window menu lists it.

Restarting Finder (Force Quit via Activity Monitor) recovered all windows - yet they were ALL displayed on the iMac - none were restored to the LG display.

Restarting OSX fixed the missing Safari window; Terminal only came back with ONE window - but I actually think that is a separate issue, cuz I"ve observed in the past that all its windows do not seem to survive a restart; only one is displayed

This issue was also observed during Big Sur Beta testing - but its "random" nature frustrated any attempts at reproducing.

I found a workaround for this.

1. Go to Display settings

2. Click Mirror Displays

3. Wait until the screens are mirrored.

4. Unselect Mirror Displays

5. Voila ...

This worked for me. Thanks Jparishll!

Issue:
My external Monitor stopped working after upgrading to BIG SUR.

Computer Setup:
I have a usb-c adapter connected which allows my external monitor , network, and I plugged my power in usb adapter and speaker to connect...


Fix that worked for me:

1. I first unplugged adapter

2. unplug power from adapter

3. reconnect adapt WITHOUT (Usb-c )power connected...FINALLY External monitor was found and displayed

4. Then plugged in usb-c Power to adapter

Possible Explanation:
Some drivers might no be loading via adapters when Power is connected to it. Basically reconnect everything without power and then connect power to adapters...

Same issues, after awaking from sleep mode, all the applications are off screen.

MacBook Pro (15-inch, 2018)
LG 34WK95U-W

Having the same issue(s) with my DELLP2715Q on HDMI via external apple dongle on my book pro 15 2018.

After the Big Sur update - wake from sleep does not restore my external display windows correctly. They are all shifted left off screen (the shadow on the left side of the external display proves they are there)

The only way to recover is to either lower (in Sys Pref) the Display scaling preference or set it back to default. Completely reproducible. Mirror windows also works. So generally seems like after wake the external display scaling resolution is not restored correctly and the OS believes it is larger than it actually is. This affects all virtual desktops also.

This is extremely frustrating - Apple recommends re-installing but I'm not sure what that's going to do - any apple engineers around to address this?

2013 Mac Pro. I am running 5 (!) older Eizo displays via DVI/Thunderbolt adapter. Since upgrading to Big Sur only 4 of them work at a time. Tried every combination, every socket, every sequence. Tried mirroring, changing resolution, restarting. Tried new cables, old cables, adapters with and without power supply. Doesn't work. Only 4 displays run at a time, never all 5. It worked like a charm 6 hours ago before the update.

Waiting for a bug fix.