Mac Mini (M1) 2020, LG UHD monitor flickers on dark colours.

It is happening when the monitor can not display particular color. Please do the following adjustment, you may fix the issue.

choose Apple menu > System Preferences, click Displays, then click Color. Click Calibrate. Display Calibrator Assistant walks you through adjusting your display, then creates a calibrated color profile. 

Has anyone tried new 11.5 RC macOS? I cannot try it as I have only one mac and it is my working horse machine. But would appreciate if anyone can try it. Because if it is not working I will issue replacement for my mac so warranty will remain and I will issue new replacements every month until they fix the issue or give us machines that will work. In worst case I will ask for refund if they release new updated macs with Mx chip.

Just updated to 11.5 today as I saw new update was available, nothing is fixed... :( now this makes me pretty angry about apple as I have never experienced any serious errors like that before. But this one is slowly eating my nerves and impairing my work.

I'm pretty sure it can be patched using software. The problem comes up when certain colours are displayed. I can't see the pattern to it, so it is probably something in the driver specifics of encoding the image before it is sent to the various output devices. I'd really like a fix for the resolution dropping when a screen saver is used - that bugs me even more than the flicker and line problem - dropping from 4k to 720p and forcing me to reboot to get the resolution back up to 4k. Should have bought the iMac and dongle spaghetti to make it useful.

FWIW, I just purchased the latest LG 27UP600-W and it works flawlessly with my M1 MacBook Air. I am connecting via a certified USB-C to HDMI cable. Using at full 4K resolution with the monitor set to DCI-P3 color mode.

MatejP84 wrote:

I have two monitors, one is USB-c-DP and other is HDMI-HDMI, the first one is also working flawlessly, but HDMI is the big pain...

Are you using an HDMI certified high speed HDMI cable? How long is it?

I have this same problem. Vertical lines on dark colors.

At first, I had another problem with my 4k monitor: low frame rate. I bought a new dock and a new 8k Display Port cable and solved the frame rate issue. Smooth as an oiled billiard ball.

But the flickering and vertical lines on dark colors persists.

Monitor is an LG 32UN500-W.

Anyone with a fix or we need to wait for Apple to throw us a bone?

Hi Pedro, can you describe the low frame rate issue a bit more? I have the same problem with my BenQ display. And what benefit do you have from the 8k Display Port cable since your new display has a 4k resolution? Why don't you use the HDMI port?

Thanks!

Not sure how to check that, but I connected same monitor with same cable to windows PC and it works OK on 4K and any lower resolution. Cable is about 1,5m long and in windows it shows HDCP ok status, so it should probably be ok?

Only thing I have changed is that I had to enable MHL on monitor as without it I only got 30Hz. But as said, same cable, same monitor, same settings works perfectly on windows PC.

Visited the AASP to check on my M1 mac mini after MLB replacement. Flickering vertical lines on dark areas of the screen even in recovery mode still persist. Funny that even the AASP certified tech could not figure out a fix for these issues. They tried their own service monitors and they were able to replicate the issues even after the MLB has been replaced.

What a pain!!! Already talked to 7 senior tech advisors in the past 57 days since I first brought the unit to the AASP. Not one of them was able to help. They are just good in intimidating you and in making promises, etc. I've already asked for a replacement but nobody cared to have it replaced.

The AASP could not do anything else based on their service guide. 57 days and counting, 2 service reports uploaded...

Using Calibrate eliminated this issue for me immediately. My setup: Mac Mini M1 > HDMI > Philips 328E1

Apple menu > System Preferences, click Displays, then click Color. Click Calibrate. Display Calibrator Assistant walks you through adjusting your display, then creates a calibrated color profile.

I just stepped thru and saved the "calibrated" profile without making any changes, and it worked.

RichardEGrant wrote:

Okay, not 100%. Spoke too soon, but it corrected 50%+ where the issue occurred. It is variable depending on what images are on screen, even scrolling a webpage up/down makes it appear/disappear.

Turn off "auto anything" or "dynamic anything" or "special enhancement modes" on your display and only adjust brightness and contrast to get a pleasing image and test what happens. Also, if there is a sharpness adjust, set it to the middle of its range. If the display works without issue, then start turning these features back on one at a time until an offending display feature is found.

Several have resolved all their issues by disabling just one or two of those special features fixed everything.

Confirmed by a senior tech advisor (from my open case with Apple):

Apple warranty policy does not allow us customers to have our unit (mac mini M1) replaced. Repair, repair, repair it is.

Worse, you will have to wait when they decide to provide the replacement MLB; worse still, you will have to make the follow up with them; they will not come back to you with updates on your service request; worse still, there is no assurance of when and if the replacement MLB will fix the issue.

Our display woes are not recognized by Apple. I asked the service advisor if there's an internal memo about this issue or anything related to it and possible fix(es): there is none. Nada. So if there's no official issue, then there's no official fix. As simple as that.

Whatever "fix" we try here online, they are just temporary or are just band-aid solutions.

Yes. I totally agree with you. Apple needs to pay attention to this issue. They cannot just bring a product, especially the Mac Mini, since it doesn't have a display to begin with to the market that is supposed to work with only a few selected monitors, that too without any disclaimer on their website. They need to FIX this.

Same problem here on M1 Mac mini and M1 Air. Tried thunderbolt > HDMI cable, $100 HDMI 4K60 cable with the same result.

Also noticed that the problem occurs more often with darker backgrounds and in dark mode.

In my case I'm using Samsung U32R59 monitor.

Definitely a software/driver issue - color profile change in most cases fixes the issue, but not permanently, as is different profiles have this glitch in different situations.

macOS 11.5.2

Resolution: 5120x2880 (5K/UHD+ - Ultra High Definition Plus)

UI Looks like: 2560 x 1440 @ 60.00Hz

P.S. Scaling change also doesn't help.