I am am running in FSDT Dallas airport
As clearly explained on the manual, and as discussed so many times on the forum, in order to see passengers in jetways, these MUST be SODE, which can be either replaced automatically by GSX (if the scenery is default), or must be replaced manually, following the instructions on the manual and the two video tutorial posted in this same section of the forum.
FSDT KDFW hasn't been updated to SODE jetways so, it basically just like any other 3rd party airport that must have the jetways replaced first, in order to see passengers in.
As already discussed many times on the forum, we are updating all our older sceneries to support SODE, but they are still not all done yet.
Right now, the following FSDT sceneries use SODE:
KSDF
KCLT
KMEM
KIAH
CYVR
KLAX
KLAS
JFK V2
LSGG
The following ones are still yet to be done:
KDFW
PHNL
Hawaii airports
LSZH
KORD won't be updated, since we are remaking it from scratch.
Of course, passengers will always work on a parking in the open, with a bus+stairs.