There is a Header Type module (6 pin Weatherpack with a molded over rear end) on the header. This sets the combine to one or 5 settings...Corn, Draper, Grain, Pickup, Other. The wiring pattern to this module determines which it is, as each wiring pattern results in a different "sense" voltage. I suppose wiring could cause a "type" problem, but its unusual. Normally a broken wire would result in a "undefined header" error.
Is it possible this head had or has "off-ground" drag rod sensors under it? I know on our Headsight off-ground systems, we add an adapter harness in between the combine and head, deliberately change the header type to grain. Just a thought.
It actually shouldn't matter which header type it is. I know that on a 3020 Grain head, pulling shift is supposed to turn on the valve to switch to the pressure adjust. More likely, the wire to the "swap" solenoid on the head is broken, or the valve is stuck. If that valve doesn't work, the reel will go up/down instead.
I would also check your settings in Toolbox>>Head 1 & 2. There may be one to turn on the flex pressure adjust. Lots of stuff that can get turned on and off, can get complicated sometimes.