Must unlock button "developer tools" .Find all day today-think bluestack not have and superuser too. Nox player have root and developer tools but use owna camera, not from notebook. And photo=mirror. Bluestacks use camera from notebook but when want do selfie-stopped after photo
Its just an emulator so all the functions which are designed for android device may not work properly.
Seriously you are trying to take a selfie with your notebook?
You don't own a smartphone in 2020 even?