You are not saying which jetways you are referring to but, assuming you are referring to GSX replacement jetways, you haven't said which airport you are referring to.
Assuming you are referring to default airports, GSX replacement jetways are placed *exactly* in the same place as the default Asobo model they replaced, and they also have the exact dimensions, meaning they will be exactly in the same position as the original ones so, if they original ones were misplaced, GSX's ones will be misplaced exactly in the same way so, clearly, is not a GSX problem, but a problem of jetway placement in the original default scenery.
Under the default airport category, there's a sub-category which are the Asobo/Microsoft Handcrafted airports. As the manual explains, these are not all made in the same way, some are just enhancement of buildings using the same parking data as the default scenery, some have minor difference in parking positions that might not be enough to cause issues to jetways, some might have bigger differences so, the "Exclude 3rd Party button" won't automatically exclude all Asobo/Microsoft airports automatically, leaving you a choice between keeping the original Asobo model or replace it with GSX models. Those with misplaced jetways should be excluded manually in the GSX Config Panel.
If, instead, you are referring to 3rd party airports, you are NOT supposed to use GSX replacement jetways there because, even if you might "see" the jetways, they will never work correctly, because they are associated to parking spots as they were in the default scenery so, unless you have a very rare situation of a 3rd party airport that has exactly the same parking spots, with the same names and positions as the default scenery, you should always be sure they have been excluded. Which is what GSX does automatically, when you install it or run an update, but the automatic exclusion relies on 3rd party packages being named using the Marketplace naming standard of developer-airport-ICAO-airportname, if a package doesn't comply with this standard ( lots of freeware don't ), it won't be automatically detected from Jetways exclusions, so you'll have to manually add its ICAO to the Disabled list in the GSX Config panel.
