I'm using the FSDT version. Purchased direct from FSDT website.
Assuming you updated it to the current version ( CYVR has just been updated ), where we added some extra LOD levels to jeways, which should help with Xbox compatibility, what you are reporting is likely the sim aggressively culling objects to get the last bit of performance, which sometimes results in things removed, depending on the view angle.
I guess this is a problem for any animated object that changes its size during the animation, the sim is still assuming the object size based on the original ( unextended ) bounding box, which is not valid anymore when the jetway extends, but it doesn't seem to be taken into account.
Nothing we can do about it, we'll report it as a bug, because it affects other animations too ( like walking characters )