I tried it just now, and it works perfectly fine, see the attached screenshot.
Are you using a 3rd party AI traffic pack that generates a lot of AI ? If yes, it's possible the two programs together have exceed some kind of (not documented ) limit on the maximum number of objects in a scene.
If this is the case, you might try reducing the quantity of AI. And, from GSX, you can try the new option in the GSX Config Panel in the installer, to disable "Ground Clutter" created around jetways so, on performing an Update, a lightweight version of the jetway replacement files containing only jetways will be installed. This will help keeping the maximum number of objects in the scene as low as possible.