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

The pre-Mojave version works a treat.   I switched back to this when the problem first arose,  but after about 3 months I upgraded again , but had lost my timemachine backup, so could not restore to the previous version.   It is great to get the link to the previous version, so thank you. 

Another workaround if you do not want to rewind your version,  is to change the resolution on your Mac.   It only seems to occur on the default resolution, either scale up or down.  It is definitely a Microsoft problem and related to the screen solution

I have  tried changing my screen resolution the flickering still occurs, it can take anywhere from a few minutes to a week or so to appear but unfortunately leaves outlook unusable, unless I run windows under Parallels.

The pre-Mojave version works a treat.   I switched back to this when the problem first arose,  but after about 3 months I upgraded again , but had lost my timemachine backup, so could not restore to the previous version.   It is great to get the link to the previous version, so thank you. 

Another workaround if you do not want to rewind your version,  is to change the resolution on your Mac.   It only seems to occur on the default resolution, either scale up or down.  It is definitely a Microsoft problem and related to the screen solution

Seems to me we need to get the version of outlook that was runing BEFORE the Mojave upgrade and install that. Lets start from there. What was the Outlook Version back then?

Believe pre-Mojave would be more more less 16.15 , July 2018 or 16.16 August 2018- try and let us know .

Link.....

https://docs.microsoft.com/en-us/officeupdates/release-notes-office-for-mac#september-2018-release

Seems to me we need to get the version of outlook that was runing BEFORE the Mojave upgrade and install that. Lets start from there. What was the Outlook Version back then?

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.

Thanks Luke I'll definitely give that a try.

I have taken to running office 365 under parallels its fine, Microsoft have told me that they will not be make a fix for this issue which is annoying as were paying to use the software.

All the problem started with an office 365 update a few weeks after installing Mojave.

I do try opening outlook on the Mac occasionally but it still makes the screen flicker after a few minutes, I give up and go to Parallels.