Mac screen background constantly being set to black

Question

Level 1

18 points

Mac screen background constantly being set to black

My M4 Max MacBook Pro's second external screen is constantly being reset to a black background for some reason. I don't know what is causing it. To solve it, I can go to Settings > Displays and adjust the scaling (text size) for any display and it corrects itself. I run the MacBook with two external screens and the MacBook closed in a stand. The main display never gets the black background.

I wonder if BetterDisplay or the Dell Peripherals Manager (which I have for a webcam) could be responsible for this, as it started happening some time after installing them. I suspect the Dell program because it also puts funny green and yellow boxes on my main display for no reason.

Anyone experienced something like this? I've seen other mentions of it happening going back some years.

MacBook Pro 16″, macOS 15.5

Posted on Jul 28, 2025 10:22 AM

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Answer 1

den.thed

Level 10

89,032 points

Jul 28, 2025 11:21 AM in response to idjwert

Serial numbers not model numbers create a path.

Without more information, all I can suggest is...

1) try moving the Dell to a different port on the Dock.

2) up the Dell's USB-C to DisplayPort cable to a high speed cable.

for example > https://www.amazon.com/dp/B09NVV76FH/ref=sspa_dk_detail_5?

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Answer 2

den.thed

Level 10

89,032 points

Jul 28, 2025 11:01 AM in response to idjwert

What make and model are the external displays..?

How is each display connected to the M4 MacBook Pro..?

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Answer 3

idjwert Author

Level 1

18 points

Jul 28, 2025 11:06 AM in response to den.thed

A Dell monitor is the one getting the black bacground, and an Asus monitor is not affected (my primary display). They are connected via USB-C/DisplayPort (the Dell) and Thunderbolt (the Asus) via a Kensington Thunderbolt 5 dock. I think the exact models are not relevant and could create a personally identifiable fingerprint.

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Answer 4

idjwert Author

Level 1

18 points

Jul 28, 2025 11:52 AM in response to den.thed

den.thed wrote:

Serial numbers not model numbers create a path.

That's not how (web) fingerprinting works.

If you can explain how knowing my specific monitor models would help you, maybe I would provide it. You need both not just the one that is malfunctioning? That doesn't make sense. What do you know about some specific monitor models that would relate to some software setting the desktop background to black?

At most the interesting part here seems to be that it is a Dell monitor affected, and I suspect the Dell Peripheral Manager (which also managers monitors). I'm having trouble updating that software.

What port they are connected to or the speed of the cable... What would that have to do with the background being set to black on an OS/software level? When it didn't happen for a long time, only recently?

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Answer 5

den.thed

Level 10

89,032 points

Jul 28, 2025 10:33 AM in response to idjwert

That sounds normal if and when the App on the main display is put into Full Screen mode.

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Answer 6

idjwert Author

Level 1

18 points

Jul 28, 2025 10:51 AM in response to den.thed

It seems to be happening at fairly random times. It is a new behavior as well, this didn't happen before.

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