The problem cannot be related to the 3.7.5 update, and from your report it seems GSX couldn't find the jetway, so it assumed the gate has only stairs.
This might be a scenery conflict, or a simulator issue, which caused the Navdata API to report GSX there are no jetways, a GSX log would confirm this, and check if you got a "Bad jetway data" in the menu.
Another possible reason is using an outdated GSX airport profile for an airport that has changed, or just the wrong GSX profile (not made for that airport), or having multiple GSX profiles for the same airport (you should have only one, the correct one).