Hi Kent
This is odd, indeed. Did you try with a different presentation? Maybe the presentation you were working on got corrupted somehow. If so, you might be able to fix it by using File > Save As and choosing a different file format, such as the old PowerPoint
.ppt file format. Or perhaps open it in PowerPoint online in OneDrive or Sharepoint, make a trivial change, then download it back.
Please go to the PowerPoint menu and choose About PowerPoint to display the version information. If you are up to date, it should be 16.21
If you have any other version, please install updates, then test again.
If your Mac is managed by an IT department, have them install updates.
INSTALL UPDATES
Make sure your Mac has a working internet connection before checking for updates. Install Mac OS X updates followed by Office updates.
Install Mac OS X updates first:
To get Mac OS updates, go to the App store on your dock, and then click the Updates button to reveal available updates.
Then Install Office Updates
To get the update:
- Open any Office application
- Go to the Help menu and choose Check for Updates
- Let AutoUpdate check for and install updates
- Restart your Mac
If you have any add-ins such as WebEx, Mendelay, EndNote, Zotero, TypeIt4me, etc it is essential that you install the latest updates for your add-ins. This includes font management add-ins, such as Suitcase. If you use Suitcase, you should have at least version 9.
Your copy of AutoUpdate may be too old to run in Mojave.
If you were told no updates are available, you will have to install the current version of AutoUpdate. Download, install and then run the latest version of AutoUpdate to update Office.
https://go.microsoft.com/fwlink/p/?linkid=830196