Looking back at threads of 3 years ago I finally understand. Problem was I could not find an option that worked consistently. On any default airfield, whether jetways move or not, or move but do net reach the target aircraft, varies according to the parking position. Nothing to do with GSX just typical Microsoft ………
EG just tried 10 parking slots at default EGLL all with jetways and on only one did the jetway link correctly to the aircraft!