Additional meeting and call-related features and issues within Microsoft Teams for Education
Try this -
- Click 'More actions' (3 dots)
- Click on 'No background' or select a background
- Apply and restart video
One scenario when this happened (selfie view disappearing from viewfinder) - tried to change background, previewed it, but then just cancelled it. The problem is when you preview, Teams stops your camera so people don't see you trying out all the different backgrounds available and acting like a fool (lol). But then when you don't select one and just cancel the pane, the camera stays switched off. Hope this helps!