Jetways are not handled in by the Addon Manager so, everything related to it being updated or not installed, doesn't apply to jetways.
AES is surely able to cause jetways to disappear, since it's supposed to exclude them, in order to replace with its own. Since you said they work in AES 2.08 and stopped working with AES 2.10, it's clearly something related to the update.
In fact, there's a thread on Aerosoft forum, with a fix for KLAS:
http://www.forum.aerosoft.com/index.php?showtopic=43472