My issue is explained in more detail on my thread (
USB Loader GX Only Works After Running Nintendont)
I have a Y cable plugged into both ports on the back, with the data plugged into the top port. Another HDD plugged into the front port is for Wii U games.
Everything works correctly when the front (Wii U) HDD is disconnected.
If everything is connected, I get stuck at "reinitializing devices" and require pulling the plug.
If everything is connected and I open Nintendont first, exit back out and then open USB Loader GX, everything works.
I was open to it being a power issue (as there were two HDD connected) but even if I wait 15 minutes between exiting Nintendont and opening USB Loader GX everything works (I assume this would be plenty of time for the vWii to "power down" the USB ports.