Flashing External Monitor When Closing Lid

[ristianchrathke]

I have an external monitor for my work from home setup (an HP 25es) That I'm trying to use as a primary monitor with a wireless mouse and keyboard. The issue I'm running into is that when I close the lid on my MacBook Pro (13-inch, M1, 2020) I get a flickering display with vertical and horizontal lines (see video attached)

This only appears AFTER the login screen, and happens regardless of the user logged in. I have tried the following:

1. Changing Power Adapter Settings
2. Changing Refresh Rate (My options are 60 or 50Hz, and it happens on both)
3. Changing color profile
4. Switching Cables (tried a thunderbolt->HDMI adapter and a thunderbolt->HDMI cable)
5. Switching ports on the monitor
6. Attempted with a windows machine, works fine
7. Resetting PRAM (Cmd+Shift+P+R on boot)

The Login part seems indicative of an internal user software problem. I'm running MacOS 12.5 but had the same issue on 12.4.

Let me know if I'm missing details here.

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[bogdanw]

I’m new to laptops … I’ve set the external monitor as Main display, the internal one as Extended, leave the lid open and turn the brightness of the internal one to the minimum. It seems turned off.
On Intel - DisableMonitor-3.0 https://github.com/epalzeolithe/DisableMonitor-3.0
but it did’t work for me on M1.
I haven’t yet tested Lunar https://lunar.fyi/
https://github.com/alin23/Lunar

 

[ristianchrathke]

I’m new to laptops … I’ve set the external monitor as Main display, the internal one as Extended, leave the lid open and turn the brightness of the internal one to the minimum. It seems turned off.
On Intel - DisableMonitor-3.0 https://github.com/epalzeolithe/DisableMonitor-3.0
but it did’t work for me on M1.
I haven’t yet tested Lunar https://lunar.fyi/
https://github.com/alin23/Lunar

I appreciate the thought here, but I have the laptop in a desk drawer, and was hoping for a closed lid solution.
I often lose my pointer on the second monitor when the lid is open, and the issue only happens when the lid is closed,
Let me know what you think, and thanks for the reply!

 

[bogdanw]

I’ve only seen that kind of behavior on a display when there is some defective hardware. But that’s not your case.
I use a cheap USB-C to HDMI adapter and it only outputs 25Hz or 30Hz. I tried with the lid closed and it works.
Other than installing Big Sur, I don’t think there is something you can do with software.
Try to find another adapter to test.

 

[BanditoB]

So, to paraphrase, you have the MBP running open and the HP display is working fine. Then, you close the MBP and the display gos bonkers. Or, you boot up the MBP closed, everything is okay through the login screen, but once logged on the screen goes berserk. In either case, what happens if you unplug and then replug in the HDMI cable? What happens if you power the monitor off and on again? Do you have a custom configuration (resolution, scaling, or something else) set up for the monitor when you're in MacOS?

I'm not sure if any answers to the above questions will help in determining what's going on, but they might be helpful.