Someday, it just stopped reading it. Tells me nothing. I've tried both ports on the back of my Wii U. One port the indicator light on the HD stays solid, one it either doesn't turn on at all or blinks semi-rapidly. But in neither case does it recognize it anymore. It used to, but it just stopped one day. Edit: By nothing, I mean it acts like there's no Hard Drive. Or at least, says USB Device not responding.