Is there a limit of six "assigned to channel" user selectable functions on the GT?

I am setting up the Spirit GT with Geolink 2 and the right column in the Spirit Settings desktop app does not populate any additional blank entries after the sixth selection.

I still have 3 channels left on FPORT, I am using only 1 through 13 at the moment. I will need to rethink my feature set a little if I am limited to 6.