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

Hi Chris, welcome to the party. In the meantime just put your computer to sleep and wake up again should correct it. Much more efficient than restarting. Give the usb-c cable that was included a try. It will function the same but I have yet to experience the pixel shift after a few days.

I have this issue too, but it happens randomly when I wake up my MBP. So far, it happened twice since I bought it two weeks ago. But I don't think that's M1 problem. I"m using 2019 16" MBP with LG Ultrafine 27 5K display (27MD5KL-B, made in China). I tried to change the screen resolution and still no lucky until I reconnected the thunderbolot3 cable.

Since there is no power switch on the monitor, I tried unplugging and plugging it back in. Did not solve anything. BUT, if I put the monitor to sleep and immediately wake it, the vertical shift is gone. Saves having to reboot the Mac Mini.

I can confirm that my problem is now resolved with the new OWC Thunderbolt 4 Hub that I purchased. The line doesn't appear anymore, fingers crossed that it doesn't come back. Will give it a couple of days and report back if the line appears again.

Am using the T4 cable.

I substituted the LG Thunderbolt cable for the Apple thunderbolt cable and I have not had any issues for the last few days.

However, I believe the power cord receptacle is not of the highest quality...I will lose the connection when I adjust the monitor and then have to fiddle with it for the power cord to make a good contact...I will look for a similar power cord and try that.

All in all I am very pleased with the actual display ... it seems the hard hardware is not up to par...

I think most of us are in the same boat. I also have the MkII version of the monitor manufactured Dec 2020.

The most believable theory I've read on this is the way MacOS is attempting to render the 5K resolution - by using 2 x 2.5K signals. This looks like a bug, whereby MacOS occasionally (for whatever reason) fails to sync the signals properly.

I personally only ever get this after the screen has been asleep after a period of inactivity and briefly reverting to a Hot Corner (ie. forcing another monitor sleep / wake) resolves.

It is extremely annoying though, significantly de-valuing the monitor's sell on value if it has a well known / unresolvable bug. If Apple cannot resolve this, they should offer customers who bought through their store a full refund - or option to trade for the Pro XDR discounted by the LG5K's purchase price.

I had the exact issue with my LG 5K monitor (27MD5KL-B, manufactured 01/2021, assembled in Mexico) and Mac Mini (M1, 2020) when I used the Thunderbolt cable that came with the monitor. It is really an annoying problem for an expensive monitor recommended by Apple itself. The problem seems to go away when I used the supplied USB-C cable. It has only been a day since I received my computer and monitor. With the USB-C cable, I am running the monitor at the scaled resolution of 2560x1440. Although the maximum resolution that can be had with the USB-C cable is 4K (3840x2160), not 5K, I think that all 5K pixels (5120x2280) are activated to produce the 2560x1440 image. Therefore, I believe that there is no loss of resolution when used at 2560x1440. In other words, the 2560x1440 image produced with the USB-C cable should be identical to the image produced by the Thunderbolt cable at the same scaled resolution where 4 physical pixels produce 1 scaled image pixel (this is where my understanding might be wrong). Perhaps, the only difference is the throughput of the USB-C cable is half of the throughput of the Thunderbolt cable. I am not a computer expert, so I don't understand the full implication. I was about to return the monitor when I discovered the USB-C solution suggested in this forum. My understanding is that as long as the scaled 2560x1440 resolution is used with the USB-C cable, this workaround is "perfect". However, if you use the USB-C cable to display a 5K (5120x2280) image, then 4K is definitely a step down. If I go through the trouble of replacing either the computer or the monitor or both, I don't think the problem would be fixed from reading all the posts in this forum.

It seems that cabling itself isn't the issue but the Thunderbolt Protocol. Others here have reported that using the USB-C cable that came with the monitor instead of the TB cable has stopped the pixel shifting issues. However, not everyone wants to utilize this possible workaround because using the USB-C limits your display to a max of 4K instead of 5K. I get that, you spend almost $1500 on a monitor and you shouldn't have to downgrade it like that.

I decided to use the USB-C cable because the pixel shifting was happening too often for me. It was annoying. I don't want to have to sleep the mini or reboot it or keep unplugging something that often. I shouldn't have to. So I used the other cable instead.

I keep default setting so it looks like the x1440 resolution. It was default for the 5K but its considered scaled for the 4K. It seems fine right now. I'll see how this goes. I'd like to go back to the TB cable soon though.

I'm wondering though. Is this something that can actually be fixed via firmware in either the mini or monitor?

Hi. I have a Macbook Pro with M1 and using the USB C cable that came with the monitor fixed the problem. Not a great solution but at least it works until there is a real fix.

problem solved for me with 11.5 ! six months to resolve Big Sur problem with this screen

the problem came from Apple and not LG

unbelievable

I'm having the same issue with my new M1 MacBook Air. Putting it to sleep and waking it back up fixes it temporarily.

I didn't experience this when using the display with my 2015 MacBook Pro via Thunderbolt with the Apple Thunderbolt 2 /3 adapter.

I bought the LG Ultrafine 5K a few months ago and love it. When I first used it with my macbook 2018 i sometimes noticed a jittery band that shifted pixels in almost the very center of the monitor. I was panicked because I had purchased the LG in order to prevent eye strain and replace a crappy monitor. Fortunately, the jiggly band of doom disappeared on its own. Fast forward to yesterday - I replaced laptop with Mac Mini M1 and after a few hours of use the vertical pixel-shifting center band of doom returned!!! I freaked out! Noooooo. I restarted everything, checked cable connections, nothing. Band, band, band in the center disrupting my work and attention. I turned it all off last night and, despairing, went to bed. This morning I turned it all on -- magically the vertical band is gone. For now. I'll update this thread if anything changes.

Hi,

you can also try the following:

• Install the app "EventScripts": https://apps.apple.com/at/app/eventscripts/id525319418?mt=12
• Open the app "Script Editor" on your mac and add the following text - key code 144 sets brightness higher, 145 lower

• Store it as .scpt file
• Add the script to EventScripts by clicking on button "Open". Copy the script to the opened directory
• Click "+ Choose" and select the script
• As Event select in the dropdown menu "Screen did wake" or "Computer wakes"
• Ensure that a checkmark is set in colum "Active"

Restart the computer and try some wakes if the pixel shift occurs. Please give feedback if it works for you. For me it works so far.

I replaced the power cable with one that I had from someplace and I do not seem to have the same issue with a loose cable. It appears that the cable that came with the monitor is slightly smaller. As far as the pixel shift goes it seems to rarely happen now. I have been keeping the computer all the time and in the evening I shut down all apps and let it go to sleep on its own. Actually, I have no idea if that practice is keeping the pixel shift from happening. When it rarely happens I just put the computer to sleep for about 10 seconds and wake it up. That seems to correct the problem. So, I just decided to live with the issue. I also changed the thunderbolt cable with an apple cable. That "seems" to have caused the issue not to occur as much. The display is perfect for my eyes so I decided to keep it after all of the these issues. If the issues really become a pain in the future I will just dump the monitor and get another 5k when more come out.