Hi Dominic, My name is Umar and I'd be happy to help you out with your question.
Please note: This is a user-to-user community forum. We are users just like you who help others. We are not employees of Microsoft.
If you're experiencing issues with screen sharing in Microsoft Teams on your Mac, there are a few steps you can try to resolve the problem:
Adjust Screen Recording Permissions:
Open System Preferences, go to Security & Privacy, and select the Screen Recording tab. If Microsoft Teams is not listed, try unchecking the "new meeting experience" in Teams settings, restart Teams, and then attempt to share your screen again.
For more information: https://www.addictivetips.com/web-conferencing/screen-sharing-not-working-on-mac/
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.'
I hope this information is helpful. Please let me know if you have any other questions.
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Best Regards, Umar Majeed