iMac screen briefly flashes black

My iMac (Retina 5K, 27-inch, 2019, OS 10.14.6) has started flashing a black screen for less than a second. It will flash once or twice, then operate normally for a while, then flash again. I tried turning off Night Shift and automatic brightness but that did not help and rebooting has not helped either. Resolution is set for default for display. I haven't noticed any common trigger for the flashes. The machine works well otherwise but the flashes are distracting and irritating.

iMac 27″, macOS 10.14

Posted on Aug 20, 2020 4:04 PM

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Aug 20, 2020 7:21 PM in response to CuNews

You can save us asking dozens of questions by submitting a report from this App for us to look at…

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/


Pastebin is a good place to paste the whole report if you capture the URL while there…

https://pastebin.com/

Whew, they've changed pastebin & made it harder, but after pasting in, click Create new paste button, then Embed button, then copy the URL...

<script src="https://pastebin.com/embed_js/KuvnghqA"></script>


The important part is...


https://pastebin.com/embed_js/KuvnghqA


Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

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iMac screen briefly flashes black

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