Apps don't show up in camera and microphone privacy settings in MacBook

I have experienced the same issue when trying to record audio with Microsoft Powerpoint 2011 on macOS 10.14. Powerpoint does not show up in the list of app with access to the microphone (System Preferences -> Privacy -> Microphone).

Note that you can reset this list from the command line (i.e. the Terminal) using:

tccutil reset Microphone

This may or may not help you. In my case it didn't.

What did help, was to launch Powerpoint from the command line through iTerm (though I suspect, using the Terminal.app works just as well). So on the command line, I've typed:

/Applications/Microsoft\ Office\ 2011/Microsoft\ PowerPoint.app/Contents/MacOS/Microsoft\ PowerPoint

I.e., I executed the executable in Powerpoint's /Contents/MacOS subfolder. By convention, every application has an executable, meaning, you can launch every application that way (but the name of the executable will usually be different).

Launched this way, when I tried to access the microphone, the System asked me whether I wanted to grant iTerm access to me microphone. After granting access, I was able to record audio through Powerpoint.

Obviously, this is just a hack to get things going. But sometimes a hack is all you need.

In my case, I won’t get the camera, mic permission prompt at all. Camera section in Security and Privacy won't populate with any app at all.

Checked the console and found out that every time I tried to use any app that needed camera/mic access, it kept throwing following error at me in Console:

Policy disallows prompt for REQ:{ID: xxx.xxx.xxx}

and

access to kTCCServiceCamera denied

I tried the method shown by @loadbox’s answer but it didn’t work for me. Turns out I had System Integrity Protection disabled. I had to reboot Mac and start in recovery mode. Started Terminal and re-enabled it by entering these:

csrutil enable
reboot

Once the machine was booted, I started Skype and voila… It prompted for Camera permission. Problem solved. Depending on your config, your mileage may vary.