Trigger Pad Mapping under MIDI focus actions.

I'm seem to be having issue mapping all of my Pads on my MPD218. BM3 is set to 16 pads, I selected Auto Learn and proceed to map my pads I can get all the way up to pad 12, once that has been selected pad number 8 switches to none. Pads 13 - 16 map just fine. Once I go to try and re-map 8 then pad 12 switches to none. Anyone having this issue? Can anyone assist?