Ran into trouble this weekend where I was unable to add permissions for a number of apps to allow access to my microphone and camera. (And yes, I’m aware of the security horrors of Zoom but I had work to do.)
They wouldn’t give the normal permissions request:
Instead, I got a message directing me to System Preferences:
Once there, the prefs did not list the app for normal check-to-enable:
I couldn’t unlock and drag on an app.
With some help from Bas Broek and this article, which specifically addressed the inability to grant access in Catalina, I discovered that rebooting with a NVRAM/PRAM reset might help. It sounded like sacrificing chicken entrails but it worked. While a regular reboot didn’t help, the Cmd+Option+PR reboot did.
Apple Support Article: How to reset NVRAM or PRAM on your Mac.
I hope this helps someone else to avoid the time I wasted.