This is the default scenery so, it means you don't have the AFCAD for the UK2000 airport. Maybe you removed it by mistake.
I do have the AFCAD, it is used by GSX when the airport is the departure airport, but not when it is the arrival airport.
That's not possible, MyTraffic surely doesn't come with the AFCAD for UK2000.
I respect your knowledge and experience, but what I am telling you is a fact - it happened. That's obviously not the right thing, so I'm asking for your help to make it right
GSX always recognizes the airport with the highest layer priority, like FSX. Be sure you install the UK2000 airport, and be sure it stays on an higher layer in the Scenery Library. You can try the "Restart Couatl and rebuild the airport cache" option, in case the correct AFCAD is not recognized.
Again, I respect your expertise, but I am telling you what happens. Even with the departure and arrival addon airports selected and at the top of the scenery menu, and with other addon airports unselected, this is what happens. I tried the restart COATL and rebuild cache option, but it doesn't change anything