cant record on a mono channel using focusrite scarlett 3

Hi there.

I am using the latest audition and focusrite scarlett 3. The microphone channel works fine and records in mono.

Trying to record my guitar in mono and it wont. I set up two tracks like this:

YOu can see stereo track 5 is recording on the rh channel where as 4 (mono) isn't recording. In a way this isn't that surprising as the mapping says right is channel 2 (if I understand it right) 

Here are my hardware settings

My question is how do I get the guitar to record in mono - I am sure it used to. I have tried altering the mapping. There aren't really any settings on the focusrite.