In Finder, go to Go at the top of the screen, then select Go To Folder. Copy and paste the folder path below (including the ~ part) into the folder path section, then hit Go. 

~/Library/Application Support




Next, within that folder, find the folder called com.apple.TCC



Drag that entire folder into the Trash (or right-click it and select Move To Trash). 

Once that's trashed, restart your computer. Open the app you were having issues with (Skype For Business, Teams, etc.) Not sure exactly at which point this will happen, but it should ask you if you want the app to have access to the camera and microphone (this may happen as soon as you open the app, you may need to initiate an action that requires the app to use the Mic or Camera). You'll want to say yes, and it should direct you to System Preferences/Security & Privacy in the Privacy section so you can check the box next to the app in the Microphone and Camera sections to. 



You'll need to do this for any app that requires Mic or Camera access (as the folder we threw out had those preferences in it), but you should be prompted by the app to approve those things. The app may not show up in the System Preferences section until you open it and it "asks" for permission to use the Mic or Camera.