The problem is not KSDF AFCAD, which is correct and as you can easily verify by opening it with ADE, includes the proper airline codes for the UPS parking in the 9-11 area AND they are properly flagged as "Ramp Cargo"
Those parking are also the largest in the scenery, at 40 mt. of radius, which should be enough to fit the 60 mt. wingspan of a 747 ( half-wingspan = radius ).
However, you said they DO park in the military areas, that has parking spots slightly smaller (35 mt.) and, they way the sim works if there's no parking code in the airplane or the parking, the sim will try to place an AI in the smallest parking that is big enough to fit the airplane so, possibly your AI go there, because they don't have the correct parking codes, otherwise they should prefer the parking spots flagged with UPS code, which we surely have at KSDF in the 9-11 areas.