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

The only think I would say with this is that I never had a problem before upgrading to Mojave. When I previous OS versions like Sierra and El Captain I never had the issues. So Apple Can say it's Microsoft but maybe it's the Apple OS. I've deleted and reinstalled the latest version of Outlook on the 18/06/2019 and it does the same thing!

I was already running macOS Mojave and this issue occurred after an Office update way back in October 2018, there was no macOS change or even an update that triggered it. It literally started after the Office update. This happened on 2 of our 2015 iMacs.

Ive got exactly the same Mac 27 Retina late 2015 and have isolated the flickering down to when I open Outlook. Apple have been unable to resolve the issue unless I take the machine in to a service centre which could see me lose the machine for upwards of a week which is a non starter as I use it to run my business. Does anybody know of a software fix for this issue?

Appears there is no hardware fix as purely a software conflict issue ....to purchase another 27" Mac of a different vintage to late 2015 to circumvent the issue appears to be the only very expensive fix  as Microsoft appears to be not able to replicate to fix this for a late 2015 issue only .

Alternatively :

1. download previous versions of Outlook until the issue does not happen .(it did not happen previously and from which version it became an issue  I do not know );
2. Use Apple Mail if Outlook is not an integral part of your life !

The only think I would say with this is that I never had a problem before upgrading to Mojave. When I previous OS versions like Sierra and El Captain I never had the issues. So Apple Can say it's Microsoft but maybe it's the Apple OS. I've deleted and reinstalled the latest version of Outlook on the 18/06/2019 and it does the same thing!

Thanks for the reply Peter Ive reinstalled Mojave and office and it still isn't resolved. its got so bad I'm having to use email on my phone rather than my MAC.

Frustrating doesn't come close!

Ive got exactly the same Mac 27 Retina late 2015 and have isolated the flickering down to when I open Outlook. Apple have been unable to resolve the issue unless I take the machine in to a service centre which could see me lose the machine for upwards of a week which is a non starter as I use it to run my business. Does anybody know of a software fix for this issue?

I wouldn't wait on MS to be honest. This issue has now been reported for over 8 months and they don't seem willing to accept any responsibility, despite the problem occurring after an Office update, which has been commonly reported!

The last thing I tried, and appeared to work (unless it was coincidence), was I booted the iMac up in safe mode and used for a few hours, then restarted as normal. I've had no issues since.

Hope this helps.

The only think I would say with this is that I never had a problem before upgrading to Mojave. When I previous OS versions like Sierra and El Captain I never had the issues. So Apple Can say it's Microsoft but maybe it's the Apple OS. I've deleted and reinstalled the latest version of Outlook on the 18/06/2019 and it does the same thing!