Assign Sends to MIDI buttons

Hi there,

I would like to assign a button on my MIDI controller (Novation Launch Control XL) to control the send amount on a selected track.
E.g. I click this button once and the Send A amount goes to the maximum value. I click it again and it goes to the minimum.

I have so far gotten this to work with a fader and pot, but Control Surface Studio seems pretty stubborn to not let me do this with a button.
I have the button set up to output MIDI CC with a minimum and maximum output. In theory, the behaviour shouldn’t be any different to a fader or pot.

If anyone has any ideas, that would be much appreciated.

Cheers,