Something changed very recently that's causing a lot of the jet bridges to not work.
First, read this thread, which explains how GSX doesn't have any effect on jetways:
http://www.fsdreamteam.com/forum/index.php/topic,16353.msg116629.html#msg116629Having said that, there still something in GSX that can affect a jetway (even if GSX itself is NOT controlling it), and it's the stop position of the airplane.
Yes, this has been changed recently (last year, with the release of KSDF) in GSX, and for the better, because now the stop position is no longer calculated by placing the center of mass of the airplane in the center of the parking, but it takes into account the preferred door position, and this is supposed to IMPROVE jetways, because if the airplane door will always be in a predictable position, the jetways will usually work there for all airplanes.
However, some sceneries might have been made using the original flawed logic of the sim, so jetways always worked with a few airplanes only: those with a door in a similar position of the one which was used as a reference by the original scenery designer, so it has always been very unreliable.
With GSX customization, if you set the stop position, if the jetway works with the airplane you are testing it while customizing, it will likely work with every airplane.
I suggest reading the GSX manual where airport customization is discussed, the chapter named "
Understanding the stop position", which explains this in more detail.
