Training: 'Z [None]' Issue 'Fix'

I wanted to put this out there for anyone struggling with the Training mission where you meet your elements and have to ask them to Fall In pressing Z but it does nothing and shows up in the bottom right as 'Z [None'.

I have 170hrs in the game and completed it a dozen times. Now I'm achievement hunting, and got stuck on 'Practice Makes Perfect' because of this. Couldn't find any reliable 'fixes' out there but I managed to figure what I was doing wrong.

Turns out, in the Options menu, under Gameplay tab, there is a few options for Issue Default Command.

I had this set to Hold/Resume, way before Training was added. Switching the slider back to Fall In is what 'fixed' it for me.

Hope this helps.