As discussed many times on the forum, whenever you have jetways missing from a scenery, it's never a problem of *that* scenery, and it's always a problem of another scenery in conflict, since the only way to remove jetways from a scenery, is with another scenery that explicitly removes jetways at that airport and/or fails to replace with its own.
Some things that can conflict and result in jetways removed:
- You installed Aerosoft AES, which removed the jetways at JFK and, for some reason, failed to replace with its own.
- You installed another JFK from another developer, so the two sceneries are in conflict.
- You have another AFCAD for JFK coming from an AI Traffic product package, which must be removed to fix the conflict.