Each time I connect using the machine control panel have to remember to click on the PORT selector and go to the bottom of a very technical looking list to select the one port that has the letters "USB" in it. Otherwise of course it won't work.
Suggest that:
a) the software remembers the last choice made for a successful connection;
b) in the absence of (a) then the sofware defaults to the most likely choice given the OS (Mac, Windows....). Probably something to do with USB.