Don't know if this has been reported, but I'm using an external windows hello camera (built into a philips 499p monitor) on a Surface laptop 3 (has a built in windows hello camera)
Running 21H1 (19043.928). When the laptop screen is open Windows hello works perfectly through the external camera.
However, when the laptop lid is closed (set to do nothing in power settings) I cannot log in using the camera, clicking the hello icon at the login screen does nothing (no error messages)
Also with the lid closed, if I log in (using PIN etc) and go into Windows Hello settings, I can improve recognition which means the camera works with the lid closed, but will not allow logging in
Hope that makes sense, can anyone help?