External display only works in clamshell mode

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Level 1

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External display only works in clamshell mode

I have a MacBook Air w/ M1chip running Big Sur v 11.6.2. It is connected to an Asus external display by way of an HDMI to adapter to USB C port in the MacBook. The power charger cord is connected to the other USB C port.

When the MacBook is closed (Clamshell mode) the external monitor display works perfectly. If I open the MacBook the external display goes totally black. How do I correct this? I have included a screen shot of the display settings in system preferences. There is no option to turn mirroring on or off. Also, while I have checked show mirroring options in menu bar, nothing is there.

MacBook Air 13″, macOS 11.6

Posted on Mar 5, 2022 8:55 AM

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Answer 1

HWTech

Level 9

68,558 points

Mar 5, 2022 11:51 AM in response to MikeLV

Are you saying that "Mirroring" is enabled? If so, then try using Command + F1 to toggle mirroring on/off. You must be logged into a macOS user account before this key combo will work.

Apple recently simplified the Display System Preferences (not sure which OS it started with) by removing some options. Since there is no "Gather Windows" option (one of the things removed) you have no way that I know of to access the other Display System Preferences window which would be on the other display which should contain the Arrangements tab/option.

Have you tried powering off the Asus display? Does the built-in display work with the cable still connected? If not, then try unplugging the display cable and reconnecting it. Do you have another video input on the Asus display such as another HDMI port, or even a DVI or VGA port you can try? Have you tried using another HDMI cable?

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External display only works in clamshell mode

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