As explained in many other threads, the ONLY way to exclude jetways from a scenery, is with *another* scenery. So, you surely have another scenery in conflict, one that for some reason the Airport Scanner cannot find.
The most common case of sceneries causing such conflicts, are AFCADs that comes with AI Traffic products, which should be used only with the default scenery, but must be removed manually if you have an addon airport.
Or, if you use Aerosoft AES, it might be an issue with it. In order to work, AES must first disable the jetways that comes with the scenery first, then replace them with its own. So, if AES succeded in the first step, but failed for some reason to do the 2nd one, the result would be all moving jetways missing. If you have AES, you must contact Aerosoft about this, because both the jetway exclusion and their replacement is happening entirely inside AES.