Sometimes it shows up, but usually it won’t. I think I understand why:
With most USB drives, the activity light stays on during the transition from the Wii system menu to WiiMC. So when WiiMC loads the list of drives, it’s still powered on and available.
With the Goflex, the light goes out and stays off til after WiiMC has loaded the drives — but by then it’s too late; the window of opportunity has been missed, and chances are, the drive won’t appear in the list.
If WiiMC had some kind of “refresh drive list” button, or if USB drives we’re given more time to power on before loading the list, drives like these (that power down while channels are loading) might have a chance.
