(video instructions here: https://youtu.be/BDGOQ-vbQ8U )
If G: Drive has disappeared or has a question mark, the software likely needs to be relaunched or logged into. Please go to the search bar by the Windows Button and type "Drive File Stream" and click on the application. It will reconnect your G: Drive and you will be good to go.
Still having issues? Check out this video link!