I know that there are previous reports on missing jetways but this is specific to the link element. After rebuilding a stock airport jetway ends (Sim Object) are visible but the jetway link (Library Object) connecting the end to a building or other point are not rendered. They appear in the unedited stock airport. Any build action on a project started from the stock bgl file seems to hide the jetway links.
I was able to create a jetway at an airport using an external tool (ADE) and build the project via the latest fspackagetool.exe. I placed the new package in the community folder and loaded the airport in sim where the links show. Editing the project in Dev Mode and selecting the jetway I created caused a CTD.
Apologies if this has been reported before with the current SU/SDK