Midi Input Instrument Select Issue

Hi All

Really need help with an annoying problem that im sure is user error but cant for the life of me figure it out. Let me start with system & software specs.

OSX El Capitan V.10.11.4

Mainstage 3 V3.2.4

My issue is ...... I have connected an M-Audio Axiom air 32 (midi keyboard) & Korg PadKontrol. The air 32 works perfectly fine as it should but the Korg, while being recognised by mainstaged in the Layout 'assign section' & midi message monitor, i can't select it in the 'midi input' section when setting up an instrument channel as only the 'air 32' shows up.

This has never been an issue before but randomly started happening a week ago. I'm assuming i've hit a setting i'm not aware of but as i say, i cant solve the issue.

Any help as always would be awesome.

Thanks

Ben