I believe to have found a bug with the addon after many days of swearing and bumping my head against the wall. (Hope this isn't some stupid mistake I did)
So, when I decide to start the sim by selecting a Gate as the departure on any airport, all of the ground services work exactly as they are supposed to, even after taking off and landing at the same airport.
When on the world map I select to just land at the airport, as an example if I select Manchester Airport (EGCC) and click 'Set as Arrival' and just land the aircraft normally, the airport ground services do not work, they will show up but only the jetway moves, nothing else, not even the follow me car.
So I believe this is a bug, or maybe there is either something wrong with my installation or with my brain, but everything should be fine (I think)
P.S. Forgot to mention I am not using any addons for Manchester Airport, and if anything this happens with every airport.