We have found that the Close Window button in the Scanned Document tab works differently based on the scenario:
Opened the SD page – new browser tab. Click Close Window button and it works – browser tab closed.
Opened the SD page – new browser tab. Uploaded a document. Close Window button does NOT work (you will have to close the browser tab)
Opened the SD page – new browser tab. Deleted a document. Close Window button does NOT work. (you will have to close the browser tab)
We will write this up, but we wanted to raise awareness. You are not stuck, just close the browser tab.