Co-Authoring in PowerPoint for Mac - Constant issues merging changes

Hi Meg

We have similar issues on PC as well sometimes. 

I tend to find in my business (where co-authoring is a huge thing for us) that using Office 365 online is the better way to go when doing this sort of activity (appliesz to Word, Excel, etc).

This way everything is online through the master document and instantly saved (doesn't have to be uploaded like the app version would do through the OneDrive client so it avoids conflicts).

If you need the full features of PowerPoint then use the app version as needed but I would suggest the more people who use the online version to made changes, the better. Especially if they are having sync issues. 

See if editing in PowerPoint online helps?

Good luck!

Cheers

Damien