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External USB-C Monitor stopped working in macOS Sonoma

I've been using my LG Ergo 32un880 on my M2 MacBook Pro since the start and never had any problems. Now, in macOS Sonoma the Display completely stopped working in terms of is not being recognised at all anymore. Someone having the same issues or any solution?

MacBook Pro 15″, macOS 10.15

Posted on Sep 25, 2023 1:49 AM

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Posted on Nov 8, 2023 6:50 AM

I had the same problem with my M2 Pro and LG HDR 4K after upgrading to Sonoma 14.2. Spoke to LG Support. They had me do a hard reset of the monitor - unplug the monitor, hold down the power button on monitor for 10 sec while unplugged, then plug monitor back in...and it worked!

30 replies

Dec 15, 2023 7:44 AM in response to Grant Bennet-Alder

I have a 2019 Macbook Pro (16 in.) that has been recently updated to Sonoma 14.2. The processor is 2.3 GHz 8-Core Intel Core i9. I have 2 Sceptre monitors (24 in.) that I am trying to connect but my Mac won't recognize them as displays no matter what I do. Since I only have USB-C ports on my Mac, I purchased a "j5 Create USB-C Dual HDMI Mini Dock (ethernet / USB 3.1 Hub (5 Gbps) / PD 2.0) w/ 4k HDMI" to connect the HDMI cords from the monitors' to my Mac. Note: I am using the HDMI cords that came with the monitors.


I have also downloaded the DisplayLink driver for macOS, which was recommended in a different forum.


There is no issue with the actual monitors (I tested them using a co-workers HP/Windows laptop and it connected right away).


I have never tried to connect monitors to my MacBook prior to this so my situation is not "it used to work but now it doesn't". I have never been able to my Mac to recognize these monitors as displays since I purchased them a few days ago.


I have tried EVERYTHING but nothing seems to work. What am I missing?

Dec 15, 2023 7:45 AM in response to scaledoctor

I have a similar LG ultrawide and the same issue. Try a hard reset on the monitor. Unplug monitor, hold power button for 10 sec. Reverse the cable. If not, HDMI->usbc will definitely work. Usbc port on the monitor doesn’t work reliably anymore. Something to do with the dual direction with power. My battery no longer charges on that port and after the upgrade the battery went bad. Terrible experience all around.

Dec 15, 2023 10:29 AM in response to scaledoctor

scaledoctor wrote:
<< using my Aten CS1953 KVM switch using USB-C.>>


the total length of the USB cable for a KVM switch that does NOT have active drivers in it is still one meter, maximum.


If and ONLY IF your KVM switch has active drivers on the outputs, (such as Docks or switches that convert to a different protocol or extract DisplayPort from USB-C) then each leg (in-leg and out-leg) is limited to one meter, maximum for USB-C, and similar lengths for DisplayPort at high resolutions like 4K.

Jan 2, 2024 8:24 AM in response to yoselm

I fixed it with a better a cable. After Upgrading to Insomnia, the monitor behind the Switch went dark. The not-working-cable was the one that was delivered with the box (I guess) from I-tec. But I still had a spare usb-c cable of high standard (I bought it a year ago for some other use), and now it works. It is 0.8m USB 3.2 Gen1. From Logilink. Best, Michael.

External USB-C Monitor stopped working in macOS Sonoma

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