LG 32" Ultra Fine monitor will not sleep on 2019 MacBook Pro 16"

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Level 1

14 points

LG 32" Ultra Fine monitor will not sleep on 2019 MacBook Pro 16"

I am using the LG Ultra Fine 32" monitor (mod # 32UP83A-W) connected to my 16" 2019 MacBook Pro (2.6GHz 6-Core Intel i7, AMD Radeon Pro 5500M 4Gb Intel UHD Graphics 630 1536 MB, 32 GB 2667 MHz DDR4 RAM, macOS Tahoe 26.0.1). Connected using the USB-C cable supplied with the monitor.

Problem: monitor will not go to sleep.

If I turn MBP off and on, the monitor will go to sleep 1-2 times when inactive. After that it stays on constantly. I have tried to boot into safe mode, same result. Reset SMC and NVRAM. Battery settings are set to "Prevent automatic sleeping on power adapter when the display is off" is toggled off. Enable power nap is set to "Never". "Wake for network access" is set to "Never".

Monitor firmware is up-to-date.

Contacted LG support without any help. Was told to contact Apple support. Apple support wanted me to perform all the above, which I had already done. No solution. The last thing they had me do was boot to safe mode and when it worked, they assumed the problem was solved. However, solved for only 1-2 inactive periods, then constantly on.

Issue was present on previous macOS Sequoia as well.

Any help to solve the issue will be greatly appreciated.

MacBook Pro 16″

Posted on Oct 7, 2025 4:53 PM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

139,571 points

Oct 15, 2025 7:56 AM in response to tor-eddie

By far the easiest way to cause poor performance, instability, overheating and crashing is to install ANY third-party speeder-uppers, Cleaners, Optimizers, or Virus scanners, Bit Torrent, or a VPN that you installed yourself.

¿are you running anything like that?

Activity Monitor can show you specifically what Apps are preventing sleep in its Energy pane. be sure you are selected (all Processes).

View energy consumption in Activity Monitor on Mac - Apple Support

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Answer 2

Oct 9, 2025 9:43 AM in response to tor-eddie

tor-eddie wrote:

I am using the LG Ultra Fine 32" monitor (mod # 32UP83A-W) connected to my 16" 2019 MacBook Pro (2.6GHz 6-Core Intel i7, AMD Radeon Pro 5500M 4Gb Intel UHD Graphics 630 1536 MB, 32 GB 2667 MHz DDR4 RAM, macOS Tahoe 26.0.1). Connected using the USB-C cable supplied with the monitor.

Problem: monitor will not go to sleep.

Issue was present on previous macOS Sequoia as well.

Any help to solve the issue will be greatly appreciated.

The new macOS are increasingly fussy over sub-par cables for connecting external displays.

It is recommended to upgrade you cable connection using high quality cables certified ULTRA HDMI or PREMIUM ≤ 1.0 m length or USB-C Thunderbolt5 cables ≤ 0.5 m length cables rated for high-speed data.

This is known to resolve issues like yours, compare your results and report back.

verify your software is up to date—

The current stable release of Tahoe including bug fixes, security updates is macOS 26.0.1

Keep your Mac up to date - Apple Support

To be proactive you can file a bug report / submit your Apple Feedback here: Product Feedback - Apple

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Answer 3

tor-eddie Author

Level 1

14 points

Oct 14, 2025 5:04 PM in response to leroydouglas

Sorry for the delayed response. I had to order a new usb-c/thunderbolt 5 cable. I replaced the cable that came with the monitor with the new one and have used it for two days. No change. Display behaves the same. Goes to sleep the first 2-3 times MPB is inactive after restart/reboot. After that it stays on until I use the on/off button on the monitor. If I didn´t mention it before, the monitor is plugged directly into the MBP and I have tried all four ports without any different results.

I've ejected my external hard drive (TimeMachine, not an SSD) thinking maybe that could cause the issue but no change. Nothing else physically plugged in.

And yes, I am running the updated MacOS, 26.0.1

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Answer 4

Oct 14, 2025 6:04 PM in response to tor-eddie

<< Problem: monitor will not go to sleep. >>

Could you please describe, in great detail what you expect to happen, and what happens instead?

Do you still have a picture on the display when this fails? Do you have a completely dark display? does it sleep the display if you choose sleep off the Apple menu?

What are the symptoms, EXACTLY?

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Answer 5

tor-eddie Author

Level 1

14 points

Oct 15, 2025 7:51 AM in response to Grant Bennet-Alder

Yes, I still have a picture on the external display. Just tried the "sleep off the Apple menu" and the display and the MBP turned off only for a few seconds. Then MBP started and display turned on with full picture (all windows open as they were before turning off).

In settings the display is set to turn off after 10 minutes (have tried all time settings) of the MBP being in-active. The MBP is set to "always" put hard disks to slepp when possible. Wake for network access is set to "never". Enable power nap is set to "never".

My expectation is that the display and MBP always goes to sleep and not only 2-3 times after a restart/reboot. When the MBP is idle for 10 minutes (or any other time setting) that the display goes to sleep (no picture, no backlight) and that the MBP hard disk goes to sleep as well. I´m not sure what other details you expect me to have. Please let me know if there are any other details you need.

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Answer 6

tor-eddie Author

Level 1

14 points

Oct 15, 2025 9:53 AM in response to Grant Bennet-Alder

The only t 3rd party from your list is VPN (NordVPN). In the Energy pane NordVPN energy impact was 95. Closed the NordVPN app and set the display sleep time to 2 minutes. Waited 5 minutes without the display sleeping.

Turned NordVPN back on and now the energy impact is 15.2, 12 hr power 92.65, App Nap "no", graphics card "no" and preventing sleep "no". Other apps listed, see picture.

Only Safari is listed as preventing sleep.

I did not have any of these issues before updating to Tahoe. Running no new apps and the use of apps have not changed, including NordVPN.

[Edited by Moderator]

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Answer 7

Oct 15, 2025 11:26 AM in response to tor-eddie

VPN:

A virtual private network, or VPN, is a private connection over the Internet from a device to a specific network. VPN technology is widely used in corporate environments. If you need to be "present" on an institutional network, a VPN is a great tool for accomplishing this. It is generally issued and controlled by the institution.

Almost all other uses are a SCAM. There is generally no need for you to have a private (and almost always MUCH slower) connection to a VPN vendor's Network, except to make it easier for them to harvest your data to sell. If you are behind a Router you control or Trust, there is NO security advantage whatsoever in using a VPN. Your connections are already encrypted in most cases.

If VPN vendors just stopped there, it would be bad. But many of these packages also insist on scanning all your files, non-stop, -- nominally looking for viruses, but who knows for sure what data they are harvesting. Their non-stop file reading punishes your computer's performance in the process.

Some also break into your other secure connections so they can be FIRST to examine your data, often leaving your Mac MORE vulnerable to attack.

https://gist.github.com/joepie91/5a9909939e6ce7d09e29

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