Be advised it can take a couple of minutes before anything shows up, even if there is a battery percentage shown on the device. And of course, Garmin Express will need to be open if you want to upload anything.
I had the the 920XT plugged in and Garmin Express open for a long time, like hours. But what I did was download the Garmin Connect app to my phone and sync the 920 up that way. Then after that my computer recognized it as well so it is all good now. Thanks.