Screen flickers, then mirrors into two exact halves whilst watching media online using Safari 14.0.1 - OS 11.0.1

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Level 1

8 points

Screen flickers, then mirrors into two exact halves whilst watching media online using Safari 14.0.1 - OS 11.0.1

wo days ago I bought a new 2020 iMac 27", i5 3,3 GHz 6‑Core, Radeon Pro 5300/4GB GDDR6, 40GB RAM and immediately updated to Big Sur 11.0.1 and Safari 14.0.1.

Watching Netflix movies in Safari the screen will start to flicker and then within a minute the screen mirrors into two exact halves. After quitting Safari I then realise that has also done the same with the finder desktop etc. And no, it isn't the window splitting function. I have exactly the same system OS and Safari on my work iMac 27", 2017 and tried to reproduce the exact scenario but no glitch.

I am specifying Safari in particular because the glitch doesn't happen, with the exact scenario using Firefox or Chrome on the effected iMac. I have attached two videos to better show what I am facing. I have not, even after scouring the internet and here, found any posts regarding this strange glitch.

Thanks for any information in advance.

iMac Line (2012 and Later)

Posted on Dec 10, 2020 6:43 AM

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Answer 1

ukstanng Author

Level 1

8 points

Dec 10, 2020 7:35 AM in response to LarsRas

I realise that from the forums here and via google search but have not come across this problem anywhere else. Thanks for your input but the theme is far from solved, not sure how that icon got there.

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Answer 2

ukstanng Author

Level 1

8 points

Dec 23, 2020 4:09 PM in response to ukstanng

I can conclude that it is almost certain in my case, that it is this very unlikely App, which is causing my specific glitch i.e. whilst watching Netflix Dolby Vision HDR media via Safari, the image will initially flicker and then the complete screen is duplicated into two separate halves, each showing a mirror image of the same. I haven’t tested for the split two-tone screen as of yet but I will keep a look out as this mainly happens while shutting down the Mac.

I came to this conclusion whilst watching the exact same media/series on the Austrian Netflix (my home Netflix) and the glitch didn’t appear, what ever I done I could not replicate it until I switched TorGuard on and played the same episodes, also different productions, on the USA Netflix site. I then carefully made sure that they were both using Dolby Vision according to the titles info text. Last test was with TorGuard set to Austria, where it was running glitch free without and bingo the glitch was back. Turned TorGuard off, the glitch was gone.

(my specs are Safari 14.0.3 on my 20.1 27“ iMac 3.3 GHZ/Pro 5300 graphic card, 40 GB)

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Answer 3

LarsRas

Level 1

42 points

Dec 10, 2020 7:25 AM in response to ukstanng

Display handling has been very poorly tested in Big Sur. I have had a number of issue (not exactly yours). I enrolled my Mac into public beta, and havn't seen my issues since (5 days now).

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