First, you are using an unsupported airplane, so in the configuration you made (or downloaded, we don't have one for the 787 in GSX by default), has something a bit unusual, which is a loaded on the left side of the plane so, one thing might be using the normal cargo instead of the bulk cargo door.
Another option, instead, could be removing the rear staircase from the parking spots used by the 787, which is done through the GSX scenery customization page.
