787 and Asobo 747-8 Fuel Burn

I am having this same issue well over a year later. MAN-SIN 25 tons short on departure and over a 100 tons FOB on arrival. Doesn’t match up with any route/fuel planning utility whatsoever. Does this have a solution or has the whole flightsim community been literally flying this sim with zero semblance of fuel planning the whole time???