Big Sur 11.1 External Display Issues!

I have posted and complained before on this issue and I believe Apple still owe us all a proper fix or reply. Following some other users who solved their issue I did the same thing once I understood what to do but not why.

I have Mac Book Pro 15 (2019), MacBook Pro 16 (2020) and a Mac mini (2021) all show the same problem with the LF 49 (4K) and LG Ultrawide monitors that I use both with HDR. For the latter I need xSwitch because Apple does not provide the correct resolution. In all cases I am using USB-C to USB-C.

I have 2 for arounds.

1 - Using HDMI from the monitor to a port replicators and these connect to USB-C on the Macs.

2 - Using USB-C to USB-C (no interim hardware), on the monitors, open their settings and change Display-port 1.4 to 1.2, if you have OSD (on screen display) Lock on then you might need to turn that off before you can change the display port setting. Now I seem to have both screens working as expected including HDR.

I do not know if this would work for other monitor brands so sorry if it doesn't help you

Hi everyone, so, with all due respect to previous posters, I wanted to try and refocus the conversation. Rather than slagging off apple or posting negative comments, let's try and make sure apple see this thread and understand the issues at hand.

The post is about the issues caused by the update to Big Sur 11.1 and the way it broke display connections that previous worked correctly.

For example, my issues are:

I have a 20" Apple Cinema Display LCD, connected to a MacBook Pro (4 thunderbolt 3 ports). It is connected with a Comsol brand USB C - DVI adaptor. I have a second identical display at another location, connected with a genuine apple USB C - DVI adaptor.

• Prior to the update, my display worked fine.

• Post update, if my laptop goes to sleep, when I wake it up my display flashes on and off like a strobe light, but only ONCE you log in.. if you leave the MacBook sat at the log in screen, the external display runs fine. Once you log in, you have to restart the laptop to get the external display to function correctly.

• Prior to the update I was able to control the sleep/wake of the laptop using the power button on the monitor. Post update, nothing.

• The MacBook Pro does not recognise the full functionality of the display under its settings.

Installing SwitchRES X has given me back recognition of the display as a Apple Cinema Display and a full range of resolutions, including recommended, experimental and above the reported resolution of the display, all of which work. I still have the flashing issue.

Lots of other users have similar problems. The issues seem universal and do not only apply to M1 machines. It appears any MacBook capable of running Big Sur 11.1 has the same issues. I have not seen a single MacBook Pro with USB C Thunderbolt 3 etc ports that is not effected.

it is CLEARLY a software issue, as on MacBooks that have the display issues with Big Sur, the display is recognised and works perfectly with bootcamp or Virtual Machines. If you downgrade to a previous OS the display works perfectly.

While my displays are old, they are still excellent screens. other people are in the same situation. The have excellent displays that cost hundreds, if not thousands, of dollars and now are, effectively, useless.

Many people have displays that do not have HDMI, USB or USB-C ports that can have their internal firmware adjusted to run on older/slower protocols.

Apple needs to either fix the problem or revert back to the display drivers and software that was used in Big Sur 11.0

If you are going to post your issue, please list the hardware you are using, ie the type of display, the adaptor and the connection. and what you have done to try and fix the problem.

"it is CLEARLY a software issue, as on MacBooks that have the display issues with Big Sur, the display is recognised and works perfectly with bootcamp or Virtual Machines. If you downgrade to a previous OS the display works perfectly."--but given the integration of hardware and software engineering in a PC this may not be a simple issue for Mac to solve--they may not be able to cleanly provide updated drivers on top of the new OS or easily provide a patch to solve these issues (or they would have done that). As you note one solution might be to downgrade and go backwards to an earlier OS. Although I can't use my Mac Mini 2018 HDMI port w/Big Sur for now it's advantages (and stability) are enough to keep for me.

The recently released 11.3 update fixed my USB-C connected external display resolution failures as well. Widescreen BenQ EX3501R QHD now working again on my Macbook Pro 16" without the hack of downgrading the monitor's display port (DP) version from 1.4.

I took the plunge last night and installed 11.3 and my monitor works on my 2019 16" but at first boot it felt like it was running 30hz. After rebooting it's feeling much smoother. I also noticed that when picking your scaled monitor resolution it no longer shows you the resolution it's being downscaled ("Looks like") from if at all (at least for my LG 32DU99 it doesn't). It does however show it's being downscaled from 2x the res properly in System Information @ 60hz.

I too have had severe issues with Big Sur monitor handling from Big Sur 11.2 onwards including crashing my Mac Mini server so that it was un-usable.

Apple support said "reinstall the operating system" which did not help.

The work arounds that were successful were:

1. buy an SIIG displayport adaptor to work with my M1 Mac Mini and download the DisplayPort Driver. This now drives three screens perfectly.
2. I found an old Kensington USB docking station that has a VGA port and a Display Port logo. I downloaded the DisplayPort Driver to this machine as well and now my VGA monitor works again and I can reboot the machine !

Clearly Apple monitor drivers went backwards in the 11.2 and 11.3 releases and Apple and Apple support have not recognised this.

Here's the fix:

Open display settings, hold the option key and click on "Scaled" option at Dell monitor settings window.

Click "show low resolution modes" checkbox.

Close the lid of Macbook.

Choose the optimal resolution for you (mine is 2560x1440) and set the refresh rate to 60Hz.

Open the lid.

If you still have 30Hz refresh rate - after previous steps go to the display settings again, choose the "show low resolution modes" and now Hz-dropdown will be available.

I was able to get get my external monitors to work after going from Big Sur 11.1 to Catalina.

it required a fresh install of Catalina

Big Sur 11.2.1 update solves the problem :)

There is a macOS Big Sur 11.2.2 update available to download. That may help you with your above stated problem.

For me the problem seems to be fixed after the 11.3-update:

MacBook Pro (16", 2019) -> USB-C -> USB-C -> LG 32UD99 32" (4k, 60Hz)

Very similar issue here, I have a BenQ PD2720U, connected with Thunderbolt 3 and it either ignores the screen completely or shows a slow and very reduced choice of resolutions. I got it "back to normal" only when switching from DisplayPort version 1.4 to 1.2 in the display itself.

I assume this is related to https://support.apple.com/en-us/HT212027 - this doesn't just plague M1 computers though as evidenced by the many posts in this thread.

I was able to get my external monitor to run on 4K resolution via USB-C after holding the "option" key while clicking on "Scaled" mode in the display preferences - unfortunately this only runs in 30Hz refresh rate rather than the monitor's supported 60Hz.

Having the same issue. My 4K LG 32UD99-W was working fine with My MacBook Pro 16" (2019) running Catalina, connected via Apple 0.8m Thunderbolt cable. After I upgraded to Big Sur 11.1, the external display works erratically, not being properly detected and only driven at 1920x1080 resolution. Needless to say this is a disaster as I work on graphics 100% of my time on the external display.

I called Apple support and tried, upon their recommendation: SMC reset, NVRAM reset, restart in SafeMode. None worked.

I then tried to connect the LG display via a HDMI-to-USB-C dongle and in that case it was driven at the correct resolution, but of course this is just a workaround and I really want to use the Thunderbolt connection, since it is also providing power to the laptop.

My conclusion is that the OS update impacted somehow the Thunderbolt driver or FW, especially if (as someone mentioned) downgrading back to Catalina didn't help.

Apple didn't really help on the phone, they seem not to be aware of the issue or at least of its severity. their last recommendation was to contact LG to check for a FW update of the external monitor...

I just bought a "USB C to HDMI Cable 4k 60Hz" and at first, I still couldn't use 60Hz for my BenQ PD2700U. I was super disappointed so I tried to install many things.

I tried to install SwitchResX, but had no luck. Still couldn't change it.

Then I installed DisplayLink Manager like it is said here: https://youtu.be/5ZgnEwHxgxo

But still had no luck. Changed the monitor settings back to DisplayPort 1.4. No change.

I was so disappointed and was ready to ship the new cable back. However, one thought occurred. What happens if I use a different USB-C slot? And that was it! Suddenly, I could switch the Refresh Rate to 60 Hertz!

And even if I put the cable in the "original" USB-C slot back. It's still 60 Hertz! So happy!