Upgraded to Big Sur, and now screen sharing doesn't work even though I granted app permissions I recently upgraded to the Big Sur OS.  Previously I was able to share my screen when using Slack, MS Teams, Zoom, and so on.  After the upgrade, I was prompted that I needed to explicitly give screen recording permissions in my System Preferences.  So I did ...

However, even after restarting my computer, I still can't share my screen.  For example, on Firefox (one of the apps in the list), I get this message

when I try and share using Google Hangouts.  What else do I need to do to enable screen sharing for my teleconferencing apps?
This screenshot indicates that you have not given any permissions.
In order to grant persmission(s) you have to click on padlock (bottom left, followed by text: &quot;Click the lock to make changes&quot;), unlock (by providing password or fingerprint) and tick apps you want to give permission to. Then you should click on padlock again to lock.
With permissions granted and locked it should look something like that: