LG Ultrafine 5K M1 Mac spurious vertical shift in a 2 inch band on screen

Hi Ross,

I can confirm that using the USB-C cable seems to avoid the problem.

I have an M1 Mac mini and a LG UltraFine 5K monitor that was purchased in November (so presumably it's the latest incarnation). It came with two cables:

• Thunderbolt 3 (USB-C) with white lightning bolt symbols at each end
• USB-C cable

I've also tried a USB-C cable purchased at a local store. Here's what I've found:

• The LG provided Thunderbolt 3 cable sometimes shows the vertical band of shifted pixels. The problem can be induced or fixed by sleeping the monitor via a hot corner, though it might take a few tries.
• The LG provided USB-C cable does not show the problem. I slept the monitor and canceled logins to get a black screen a couple of dozen times and could not reproduce it.
• The "store bought" USB-C cable does not work at all. It does not drive the monitor - the monitor stays black. That avoids the problem but it's a poor solution. ;-)

As you've pointed out, the sacrifice with the LG provided USB-C cable is that one maxes out at 4K (3840 x 2160).

I'm going to call Apple again to see where they're at with this.

Problem Solved - you can all relax now! The solution is very simple...there is none...at the moment and I doubt there will be one. let me elaborate so you can all stop wasting your time. I am referring exclusively to the Ultrafine 5K model btw:

• This model is no longer supported by LG.
• If you go to their website it will not appear as an available model, if you enter the model number it will bring you to an old product page but when you select "downloads" it just lead you to pages for their supported 4K monitors.
• I called LG and they are fully aware of the incompatibility of the monitor with Big Sur creating the pixel distortion. I spoke to several support team members at LG who all said the same thing. A new firmware update is NOT planned for this model.
• When I asked why the display manager on the App Store hasn't been updated in over a year and is thus not M1 compatible...I just got the run around.
• Spoke to several Apple support members who all claimed to have never ever heard of this issue and suggested reinstalling Mac OS and all kinds of other non-sense.
• When I pointed them to this threat and some online articles from 9to5 Mac and Macworld on this issue I was repeatedly told that Apple has no knowledge of any issues with this display not working correctly under Big Sur or on M1 computers.
• There you have it. Stop wasting your time, just deal with the distortion (use hot corners to get your monitor to sleep and wake up - it gets rid of them temporarily), OR use USB C instead of thunderbolt and go down to 4K resolution, OR bite into the sour "Apple" and just by a different monitor or wait for Apple to launch a pro version of their 24" TikTok Mac.

Switched back to the Thunderbolt cable after upgrading to Big Sur 11.3 on my M1 Mac Mini and problem still occurs (after about 12 hours for me). Always begins upon waking the screen. Only happens when using the Thunderbolt cable. Sleeping and re-waking the computer normally remedies the situation. Or, as mentioned here, you can switch to using the USB-C cable and the problem never occurs then.

OK, Using the USB-C cable resolved the issue. (Just wish Apple knew this on the phone before they had me order a replacement Monitor.)

I have the same problem too with a new LG UltraFine 5K display running from an M1 Mac Mini. I'm running macOS 11.1

The affected area is a maybe one inch wide band just left of center that runs the full height of the screen. All pixels in that band are shifted maybe two or three pixels upward. I've attached an image.

The problem is not visible when screen sharing to the machine nor when taking a screen shot.

The problem seems to be random. Unplugging and replugging in the display cable fixes it. Putting the display to sleep via a hot corner can either fix or induce the problem.

I can essentially confirm it is thunderbolt 3 that is the problem. Not just the cable that is included but the spec and how it works with the monitor (as others have said buying a new cable didn't resolve). I have had zero instances of the shift using usb-c instead of thunderbolt. If you have version 2 of the monitor there is no reason not to just use the usb-c cable that was also included with the monitor. Version 2 of the monitor supports full 5k resolution over usb-c.

Hi Steve,

That is correct. You would still see the connection under "thunderbolt" in the hardware info. Apple made this all very confusing because USB-C and Thunderbolt are really interchangeable to some degree. The only difference is the amount of data that can pass through a thunderbolt 3 cable is higher than a USB-C cable. The port can be used by both though.

Basically it wouldn't/shouldn't show up as a usb device since you are using a "thunderbolt" port.

As long as your display is pulling in 5k when using the USB-C cable you are all set and shouldn't experience the vertical pixel shift issue. From what I have read, version 1 of the monitor would only do 4k over USB-C, so this would really be the only reason why someone would be stuck using the thunderbolt cable.

I believe there is some technical issue with the design or interaction with the thunderbolt 3 cable that causes the pixel abnormality. USB-C cables seem to not exhibit this.

The USB C cable fixed the vertical shift problem on my M1 Macbook Pro, but then I read that the USB C cable only gives you 4k resolution. I didn't buy a 5k monitor to view it in 4 k, so I switched back to the thunderbolt cable and the vertical shift still appears once in a while. To get rid of it, I put the computer to sleep and immediately awaken it and the vertical shift is gone.

Sure hope Apple finds a fix for this.

No, it is not fixed. If you use usb c cable, there is no shift. If you use thunderbolt cable, you get the shift. I have Macbook with M1. I decided to continue to use thunderbolt cable to get higher resolution. I get the shift randomly, about once per day. If it happens, I put computer to sleep and wake it and that fixes it until the next time.

As of today Apple officially states that it has NO KNOWLEDGE of this display not working properly. Apple tech support still suggests its an issue with the individual consumer and suggest solutions including reinstalling the entire Mac OS. I have not hopes that a solution is on the horizon. But its OK...in my case with the M1 mini it happens on average every 2-3 days and I just put the monitor to sleep and wake it up via hot corner - 5 second fix.

That my dear is a waste of time. LG has discontinued this monitor. Apple already pulled it from their store in ALL countries BUT for the United States where I assume Apple wants to get rid of any remaining inventory. The issue is Big Sur and LG is leaving it up to Apple to fix the issue. Though Big Sur has been released for over 6 months now it has not been solved. There were way bigger bugs with this monitor under Big Sur initially that did get resolved. But at this point I don't hold my breath that this final issue of occasional pixel distortion that one can fix via hot corner (put monitor to sleep and wake it up) is getting any attention for an obsolete monitor. I had numerous conversations with LG support and was always told that no firmware update is in the works or planned.

Glad I found this thread. This vertical shift exists even in macOS 11.4 for me. However an interesting fact is that, I also use this LG 5K monitor with my 2018 iPad Pro & no such issues seem to exist at all.

Steps to retrace:

> Device - M1 Mac Mini 8GB, CurrentOS: 11.4

• Fresh startup login - No such vertical bars exist
• Use hot corners/ let display go to sleep normally - Then tap to wake up - Vertical bars appear.

Workaround solution for me:

• When i see the vertical bars, I once again use the hot corners to allow display to sleep. But, allow atleast 30 sec before I wake it up again. Then, things are back to normal. (However, if you wake up as soon as you put display to sleep - you can see the vertical bars)

In my case, the issue (see attached) was an LG hardware problem. I was under warranty. I contacted LG support. After a few e-mails, I was instructed to send the monitor in for repair (they provided the label). Three weeks later the monitor arrived repaired, and I have not experienced the issue since.

I’m also seeing this sporadically on my LG 5K with M1 Mac Mini but it also had occurred sporadically with the same monitor and same thunderbolt cable with my previous Mac Mini 2018. I noticed that unplugging the cable from the back of the monitor and plugging it back in again makes the issue go away so at least I have discovered how to avoid rebooting. At Apple support’s suggestion I’ve ordered another thunderbolt 3 cable to try to help decide if the cable could be the culprit.