Help with SOLIDWORKS section views.

I have attached a part file and a drawing file of a hollow wood surfboard I am trying to model.
There seems to be a problem that I can't resolve when I am doing section views in drawing up a set of plans.

At Cross section "FF" in the drawing document I am unable to see the cutout properly in the rib at "Rib 6 Boss-Extrude" from the associated part document. That is the cutout where the rib is joined to the stringer at Rib6. All previous cross sections have worked but not past this point.

I have experimented with different shapes etc but can't get it to work.

Any help would be appreciated.

Duke