Running Outlook on the iMac causes the screen to flicker and eventually black out and reduce to half/split screen display.

And does seem to be linked to scrolling - think it's possibly a display/refresh issue?

Hi AussieFlem and GB93,

Since the issue persist in your new iMac when running Outlook for Mac, please check if the following measures take effect.

1. Try to update to the 16.21 version of Outlook for Mac and check if the issue recurs. 
2. Please make sure there's only one installment of Outlook in your iMac since many issues caused by conflicts between duplicated installments.
3. Besides, you can try to remove the .plist files in your iMac via the steps below.

    a. Quit Outlook for Mac.

    b. Locate the following files:"~/Library/Containers/com.microsoft.Outlook/Data/Library/Preferences”

    c. Move these .plist files to Trash, but do not empty Trash and delete the files.

    d. Re-open Outlook, check whether the issue is resolved. If yes, you can delete the files mentioned above in Trash. Otherwise, please put the deleted files back to the old location.

While if the issue still exists, I suggest you contact Outlook for Mac in-app support channel via Help > Contact Support. The dedicated team focuses on Outlook for Mac issues and will provide further assistance for you. We kindly appreciate for your understanding.

Regards,

Marvin

I'm having the same issue, for private use I don't use Outlook and never have issues. When I work from home and use Outlook and Skype for Business after some time the screen starts giving white flashes. The mouse cursor on top of the white flashes stays visible and operational (can move it), indicating this is not a hardware issue.

Hi Herry,

If you're experiencing the same issue when using Outlook for Mac and Skype for Business, you can take the measures mentioned in my last reply to check if the issue persists. Meanwhile, since Microsoft is encouraging users upgrade to Teams, Skype for Business will be replaced in the future. So you can also download Teams to check if it helps.

While if the issue still exists, the issue could be related with Outlook client. And I'd like to get Outlook for Mac in-app support team involved in this issue. The team has rich experience on Outlook for Mac client issues and will provide further dedicated suggestions for you. You can open your Outlook client and contact them via Help > Contact Support. It's highly appreciated for your understanding.

Regards,

Marvin

The steps above do not resolve the issues. 

Also switching to teams is not an option if your organization does not support it and when you can't use it to call into Skype meetings.