Could it be that I should delete the LBBD gbl scenery file in MyTrafficX?
Exactly, remove the conflicting file when the sim is not running, and restart GSX. If you don't see the cache being rebuilt automatically, select the "Restart Couatl and rebuild the airport cache" option from the Couatl menu.
You always want to remove any conflicting files (and AI traffic products are the most common source of conflicts), because even if you didn't use GSX, duplicate AFCADs, in addition to wasting memory and slowing down the startup of the sim, can cause other issues like non working tower frequencies, problem with instrumental approaches, and misplaced AIs.
The AFCADs that are being installed by the AI Traffic product, are supposed to be used only as an enhancement of the default airport, but if you have an add-on airport, you should always try to be sure the sim will always use the AFCAD that comes with it, and removing the conflicting ones is the safest and more optimized way.