M1 Mini issue with LG 27" 5K Monitor

Chris,

I did not use the cable labeled USB-C MacBook iPad Pro. I used the cable marked Thunderbolt 3 (usb-c) for multiple devices, including the Mac mini.

I've used the following cables, and all have had the same issue with the pixel shift.

• two differnt Thunderbolt 3 (USB-C) cables that came with the two different LG 5K monitors from the Apple Store (one monitor was returned, believing the monitor was at fault)
• The Thunderbolt 3 cable (.8m) from the Apple Store - $39
• The Thunderbolt 3 Pro cable (2m) from the Apple Store - $129
• The Thunderbolt 3 cable that shipped with the CalDigit TS3 Plus Thunderbolt 3 Dock

In all cases, I connect the monitor to the mini directly by TB3. I connect my Caldigit TS3 Plus dock to the mini directly as well, using the second TB3 port on the mini. I then connect all my peripherals to the CalDigit TB3 dock. I currently do not use the USB-C connections on the back of the monitor.

I hope this helps

I had this exact same problem and attributed it to a monitor defect after talking with an LG technician. The LG tech said to take a screen snapshot of the defect. If the defect is not in the screenshot, then the defect is with the monitor. If the defect is in the screenshot, then it is in the signal from the computer. In my case, the vertical section was shifted up by a few pixels the full height of the monitor, with the right edge of this vertical section just left of center on the monitor. When experiencing this issue, I could drag any window, image or even the screenshot across this section of the monitor, and the pixels would shift moving across that section.

In my case, the defect was not in the screenshot, so I attributed it to the monitor as LG suggested and got authorization from apple to return the monitor. I've purchased the replacement monitor and have not seen the issue this far.

I was hoping this defect was the root of my other problem with the resolution changing to 4K, but it is not, and I'm getting a replacement M1 mini next week from apple.

Thanks for the reply, this gives me hope.

Thank you for the reply. While it's good to know someone else is experiencing the issue, it makes me wonder if replacing the M1 mini will fix it. II expect I will have to decide whether to use the LG monitor as a 4K monitor or send the mini back and wait for an M1 iMac. I tried contacting LG to ask what the latest firmware version is, but honestly, they are not very responsive. The LG screen manager software on the apple store is intended to show the version and update it, but it did not work on my M1 mini. This is the first time I've been less than impressed with Apple, and I don't want to buy into an intel iMac at this time. Best of luck, and if you learn anything, please let me know, and I'll do the same.

Meaden, did you ever resolve the issue with the section of the screen being off vertically by a few pixels. I still have the issue after replacing the monitor and the Big Sur patch. I no longer have a resolution issue anymore, just this same section in the monitor that is ocassionally off by a few pixels. Apple is sending me a replacement M1 Mini, but I'm not too confident it will resolve the issue.

Thanks for the response. I have the same thing going on and correct it the same way. Mine is always on the screen in the exact same place and width -- The right edge of my vertical section is aligns just left of the camera. Mac is sending me a new Mini, and I'll see if that corrects it. Because the second monitor is doing the same thing in the same spot, I don't believe it is a monitor issue.

Happy Holidays

The timing of my call and being within the return window likely helped me, along with getting to a senior advisor on the call. I contacted Apple right away when I noticed the issue, and they opened a case re the problem. At the time, three things were going on -- the pixel shift, blurry text and the monitor dropping back from 5K to 4K. I effectively had tried everything (software updates, restarts, different cables and ports) the Level 1 support agent would ask me to do, so I was able to get to a senior advisor during the call.

I told them I wanted to avoid sending anything back if I can avoid it, so the case was left open and got assigned to the next level of support for more advanced diagnostics. Apple was now contacting me to resolve the issue, and I have been working with the same technician for several weeks. I've run a number of different diagnostics routines at their direction and even sent a video shot from my phone showing the pixel shift. The blurry text and falling back to 4K were resolved with Big Sur 11.1 update. Since the pixel shift its still present after the update, they initiated a replacement that I am waiting to ship.

If you are correct with it being an architecture issue, the replacement Mini won't by itself resolve the pixel shift issue. I'm at the point though that I'll have to live with it and hope that it will be fixed with a firmware or software update.

Best of luck.

One other question, I presume you running the 5K monitor as an external display from your M1 MacBook Air. Is the pixel shift only seen on the 5K monitor?

I can video the shift, but any screenshots I take of the shift do not show it in the screenshot. An LG tech advisor told me that if the screenshots are good, the video signal to the monitor is good and that it's likely a monitor issue. I don't believe that is true in this case though.