I've had endless problems trying to get an M-Audio MIDISport 4x4 interface working under Windows. Half a day of googling, driver updates, registry edits, reboots and nothing was working but there was a clue in a post from (of all people) Microsoft tech support. Apparently some MIDI interfaces don't like the identifier requests sent out by USB 3.0 hubs. The solution? Use a USB 2.0 hub. Simple as that. Works first time. Posting this so the internet can share in the secret.