See what's going on from Windows point of view.
Open Event viewer (Control Panel > Administrative Tools > Event viewer).
Find the Applications and Services logs, open that branch. Then open Microsoft. Then Windows. Now, scroll down and look for Driverframeworks/Operational (something very similar, can't recall off the top of my head).
Within that one, the right-hand pane will now show every little USB event. However, ironically, I opened a post a while back trying to discuss why a USB flash/thumb drive WILL have half a dozen events in this part of event viewer, but an external portable hard drive, does NOT log any events.
Anyway, worth a try.