hi - I have same issue for about a month (3 docking stations - 2 different types) all don't have working USB although video and power work. Frustrating! did you have a fix?
I too had this problem. I spent some time on the phone with Microsoft Support this morning and was able to resolve it. Here's what they had me do:
1). Remove all cables and dongles from surface dock.
2). Unplug Surface Dock from Surface Book (or Pro)
3). Shutdown Surface Book (or Pro)
4). Press and hold Power Button for 20-30 secs. Startup screen will go Black and stop starting up.
5). Plug all cables/dongles back into your Surface Dock
6). Plug Surface Dock back into your Surface Book (or Pro)
7). Press Power Button on Surface Book (or Pro) for standard start up.
I was told that the issue was with my device holding a static charge making it unable to connect to the USB hub on the Surface Dock. The long press on startup will drain the charge allowing it to reconnect properly on next startup. Hope this helps!