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forappie Author

Level 1

36 points

Invisible highlight color on Mac Mini M1 with external monitor

On my Mini M1 (Big Sur 11.2.3) I can only see highlight color in a non-active window when I turn on night shift. When I connect the monitor to an Intel MacBook AIr (also 11.2.3) I don't have the same problem.

This happens only with non-Apple applications.

In the samples below I'm showing a TextEdit window and a Postbox (mail client) window. I ran the test on my Mini in Safe Boot to avoid problems with third-party software,

I'm using a Dell U2711 UltraSharp monitor (2011) connected via USB-C (mini) to DisplayPort using a Plugable cable (I also tested with a HDMi-HDMI connection with the same result). I must mention that I also get an on-screen message when I log in "Increase Display Contrast On". No clue where this comes from.

In the first sample below I cannot see any highlight color in the window behind TextEdit UNLESS I turn on Night Shift (second sample).

NOTE: if you don't have the problem I describe you probably will see no/limited differences between the samples!

Night Shift turned on:

Intel MacBook using same monitor and connection (USB-C to DisplayPort). The highlight color in the active window is bright red and in the in-active window dimmed red 9as it should be).

Posted on Apr 25, 2021 5:20 AM

Top-ranking reply

forappie Author

Level 1

36 points

Posted on Apr 28, 2021 7:34 AM

I contacted Apple support and could only show them the issue using the camera on my iPhone (using screen sharing the support engineer would see something different from what I saw on my screen).

A second line engineer advised me to shut down and disconnect the power for 15 seconds (from the back of the M1 Mini, ie not the power plug into the mains outlet).

After reboot my problem had disappeared. This solved the problem. NB I did not find a reference to what disconnecting the power was supposed to achieve.

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Invisible highlight color on Mac Mini M1 with external monitor

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