Microsoft Teams Mac OS client is not recognizing external cameras after updating to version 1.3.00.18164.

I had the exact same thing happen to me after updating to the latest version of teams.  However, I was able to come up with a solution that resolves the issue entirely.  It has to do with how Apple is starting to codesign specific apps to block 3rd party CoreMediaIO plugins.  If we remove that codesigning, then it will allow those 3rd party plugins to function again.

The fix is pretty simple.  First, completely exit out of Teams, then open Terminal and issue the following commands:

If you havent installed xcode previously, first run:

xcode-select --install

Then, run:

sudo codesign --remove-signature "/Applications/Microsoft Teams.app"

and:

sudo codesign --remove-signature "/Applications/Microsoft Teams.app/Contents/Frameworks/Microsoft Teams Helper.app"

Once you've issued those commands, open up Teams.  It should ask you for an administrator password to allow the (now) unsigned application to access your keychain.  Once entering your password and selecting, "Always Allow", the issue should be resolved. (At least until the next update to teams is released).

*****UPDATE*****

As of version 1.3.00.28778 the process has changed and the above workaround is no longer valid.  In order to get this fix working on the latest version of Teams, additional commands will need to be entered.  Keep in mind, these commands are relative to where you have Teams installed, so if it is in a different location, you'll need to adjust the file path accordingly.  So as it stands currently here are all of the commands (must be entered one by one and not pasted in one big block) that will need to be entered:

xcode-select --install (only if you haven't already)

sudo codesign --remove-signature "/Applications/Microsoft Teams.app"

sudo codesign --remove-signature "/Applications/Microsoft Teams.app/Contents/Frameworks/Microsoft Teams Helper.app"

sudo codesign --remove-signature "/Applications/Microsoft Teams.app/Contents/Frameworks/Microsoft Teams Helper (GPU).app"

sudo codesign --remove-signature "/Applications/Microsoft Teams.app/Contents/Frameworks/Microsoft Teams Helper (Plugin).app"

sudo codesign --remove-signature "/Applications/Microsoft Teams.app/Contents/Frameworks/Microsoft Teams Helper (Renderer).app"

******UPDATE #2******

I totally forgot about this thread and decided to take a look at it again. From the latest comments, it looks like a lot of you are already aware that this issue has officially officially fixed by Microsoft as of version 1.4.00.8872, so this workaround should no longer be required as long as you are up to date.

Source: https://docs.microsoft.com/en-us/microsoftteams/troubleshoot/teams-on-mac/virtual-camera-doesnt-work-macos