Just for giggles, I connected my SM-BCR2 just to the computer, and it shows up in device manager under "Ports (COM & LPT)" rather than USB in Windows 10. Also, if you launch E-tube with the SM-BCR2 not connected to the bike, it'll let you start the process of a connection check and prompt you to connect to the bike. If you click the connection check button with the SM-BCR2 disconnected from the computer (or if Windows doesn't recognize it), E-Tube will prompt you to connect a linkage device.
Stranger things have happened, but for the SM-BCR2 to fail in such a way that it still charges ok (which requires communication with the bike and uses the same USB port that the computer connects to) but no longer connects to the computer, seems a little too strange.