I think the extended force Icons for the platoon sized units has been left off intentionally?
I personally would like the extended force icons to be displayed for platoon sized units at this level of zoom as well.
On the next level of zoom out, they will be displayed as smaller unit icons, without extended force unit icons, which is fine.
As for the IG Platoon and other support units leading a move, I have no idea, and I don't think Dave does either