What I have realised that GSXpro and AIGTC work flawlessly in all third party airports (atleast for me) either payware or freeware downloaded. The only airports where this problem occurs are ASOBO detailed airports. I tried EGLL, LFPG, EDDF and LEMD with same problem. I you start flight without AIGTC, GSX works accurately on these airports as well but when you start AIGTC , no traffic is seen in spite of it being shown on TC map.
IF you start flight with AIGTC on, it removes some GSX vehicles and animations and VDGS.
I dont know the reason behind it, just an observation and I have no idea why this happens.
Best wishes