It turns out that the problem was really a defective/loose connector on a flash drive.  The USB socket on the front panel was fine.  Notable that I was never able to find a part number or replacement for the jack (panel).  Never did receive any information from Dell --very disappointed in Dell's (lack of) response.
[NAME], what was the outcome of this if you don't mind?
XPS 8940, defective front panel USB ports, #2