I have had this problem off and on for about a week. I installed the full GSX installer a few days ago, and still see the problem once in awhile, I call for deboarding, and I only see one truck with the stairway on it, which goes to the rear boarding door of the 737 NGX ( this is when there is no Jetway) . I used to always get a stairway truck on both front and rear. I still do most of the time, but not always. Is there a reason for that?