I think you are packing too much into GFb...with a "Keep Together" on it the entire section must fit on Page one or it will be dragged over to page 2
"
Categ ....... (How Big is this little bit??)
Categ ....... (How Big is this little bit??)
etc <...... (this scares me

, is this large??)
"
When you add these to the footer, do you block out the complete space that is required or is there "can grows" on the fields.
Now tell me...if this splits to a new page due to the above...do you want the Page header to show??...
See I am not sure when the flag is evaluated...since it is in the same section as the rest it might be done first so when you get dragged over the flag is now set already.
My suggestion is to break up GFb into 3 subsections with the Flag formula in the last of the 3.
Is it necessary for the "Keep Togethers" on the sections? I think they are made that way by default. If it looks ok with half a footer on one page and rest on another...I'd take the "Keep Togethers" off..try it and see what it looks like.
I would similarly break up GFc as well and put the reset formula in the first one.
Hope this helps
Jim