Actually it seems Swissport is there, but only selectable at certain gates. Before the update it was selectable at all gates.
That's entirely normal.
We followed the suggestion from Dreamliner787, who asked to add Airpro, saying it has replaced Finnair in all airport s *except* EFHK so, in order to keep Finnair there (together with Airpro, Swissport and Aviator), we set them all at score 4, with full ICAO matching.
So, on a default airport that has no ATC parking codes in the scenery AFCAD, they should be all available, since they all have an equal score.
On a 3rd party airport, you won't find any parking codes for Swissport, Airpro or Aviator, since these are GSX-only operators, not airlines, and they don't have a 3 letter code to insert in the AFCAD (which doesn't even support more than 3 letters), but you might find Finnair code so in that case, Finnair will always "win", since it has both a full ICAO match like the other 3, but it also has an additional score because of the Atc parking code.
So, the easiest solution, now that GSX allows to do it, is to set either all the parking affected, all set the whole airport at once, adding the parking codes in the GSX customization page, which will override whatever you have in the scenery AFCAD.