Hi guys, I'm not sure if this is the same issues I had at work but I finally got everything working on our Macs. We use video cameras, via an UltraStudio Mini Recorder, into converters, to the Mac to run live webinar training sessions. We had no issues until we updated to Big Sur 11.4 and then (weirdly only on one Mac) we couldn't share screen in Zoom (it was caught in an endless loop of asking for Screen Recording Permissions!). Nor was any device found in Desktop Video? Stress and head scratching and foul language ensued for a few days, numerous threads and forums and attempted solutions, but no success...until today!
I uninstalled, Desktop Video, Zoom, Teams, Skype, and Teamviewer (in case it was using the camera and interfering). I then restarted the Mac. Next step was to disconnect the Mini Recorder and reconnected it and made sure the power light was on. Then, I installed Desktop Video version 12.1 as soon as I opened it the device was finally found! Step one was complete. I then reinstalled Zoom and the camera option finally let me pick the Blackmagic device. However, Screen Sharing in Zoom still didn't work!!! I found a command to reset all the ScreenCapture settings in terminal (tccutil reset ScreenCapture). Then, opened Zoom again it asked for permissions so I went to preferences and manually added the Zoom app to Screen Recording and made sure it had permissions for camera, microphone, full disk access, and accessibility. Relaunched Zoom and boom, it worked! After reinstalling Teams and Skype and manually adding the Screen Recording permissions for each app, everything now works on Big Sur 11.4 and Desktop Video 12.1 and the latest versions of Zoom, Teams and Skype.
I'm not brave enough to say this solution will work for everyone. Depending on the Mac you use some systems might be different, but considering the problems and stress this caused I thought I'd share the situation and solution in case it helps at least one person.