Mine disappeared once I formatted it so disconnected it and plugged it back in and it showed up.Hope someone can put me right, I connected my new SSD drive to my XB1X via the USB port on the front of the console, then it asked my to format it if I wasn’t using it for media etc.
But when I came to look at the storage devices in settings it only showed my external HD (I got a standard 5TB drive).
The SSD drive only shows up if I put it in the USB port at the back, thus having to unplug my standard HDD.
Not sure why it won’t show when the SSD is plugged into the front port....maybe not USB 3.0?
FYI there are two USB ports on the back, are both being used?