Hi Tony,
There is no "repair Office" for Office for Mac. Usually that is accomplished by installing updates on the Mac.
Which brings up the next question: What build of PowerPoint are you using? Go to the PowerPoint menu and choose About PowerPoint to find out. The current Insider Fast build is 16.39.20061607
If you don't have this build, the first thing to do is go to the Help menu and choose Check for Updates to launch AutoUpdate. Once you have installed the updates, test again and see if the problem still exists or has gone away.
If the problem persists, while the problem exhibits, click the Help Improve Office button in the upper right corner of the PowerPoint window to report this to Microsoft
