I have the same problem with SP7 (i7) and HP G5 dock. Updated all firmware on SP7 and G5 dock, no luck. Seems like the SP7 is having trouble with it. When I disconnect the dock, SP7 will still think it's connected (displays still on, trying to charge, etc).
Also, I'm trying to run (2) 4k displays at 60hz off this dock, everything is DP1.4, but the best I can get to work is (1) 4k display at 30Hz, not even close! The display adapter settings also are buggy and oftentimes I can't even adjust one of the screens
resolutions (it's grayed out in windows display settings).
May need to go back to surface dock for 1st display & USB-C to DP adapter for the 2nd display. This is what I did with my old SP (mini DP to DP adapter) which is annoying to dock dozens of times a day.
Looking for help.