Hello everybody,
it seems like I could solve my Problem ( Bus at deboarding under the wing ).
I updated GSX Pro to V3.6.3, then I choosed the aircraft profile for my IniBuild A320 neo V2 while GSX PRO was runnning, unchecked the PIGS for Door 4 (yes unchecked !) and let the PIGS checked on only for Door 1..... and it worked!! Now the Bus is correctly placed outside the yellow strings at deboarding just like at the boarding. Can´t understand all this, but hey, it works as it should.
Pit.