Cannot get PowerPoint to Access Microphone

I am trying to record voice over PowerPoint slides that I can provide to students via YouTube videos while I am teaching online. My problem is that I get an error when I try to record audio in Powerpoint. The error dialog box says,

“PowerPoint cannot perform operation because the audio recording device is unavailable. Check to see if the audio recording device is plugged in and it is working, and then try again.”

I am trying to use my MacBook Air’s internal micophone, which I know works on other applications that I am using for video conferences (Zoom, WebEx, Go to Meting).

When I go to the Privacy setting and select Microphone, Powerpoint does not show up as an option. There are only 4 I listed (and all are checked): Go to Meeting; Cisco Webex Events and meetings; and Zoom.

How do I get other apps, like PowerPoint, to show up in the microphone setting to allow me to check them and give them acces to my microphone, etc?

My PowerPoint is version 16.37 on a Microsfot 365 Subscription license.

My computer is a MacBook Air (13-inch, early 2014) running macOS Catalina 10.15.4

Thanks.