Perhaps I wasn’t very clear on my first post. The objects missing are not FSDT scenery objects, but default library objects on default sceneries and on addons that use them. For example, if a addon scenery uses default FSX jetways/terminal buildings, they don’t show up in FSX. All the objects on the FSDT sceneries are ok.
Sorry, I misunderstood you: I thought you were missing buildings in the FSDT sceneries only.
There's one file we require to patch in the default library, and it's the vehicles_airport.bgl file, in the FSX\scenery\Global\scenery folder, and the only change we do to that file, is to disable the default pushback Truck, which would conflict with the GSX one.
So, the installer will first create a backup of the original file, named vehicles_airport.gsx, then will patch it to exclude the truck. This always work, and nobody ever reported a problem with it, but maybe something did go wrong during the installation, most likely (again), due to antivirus interference.
So, check if you have the named vehicles_airport.gsx file and, if you have it, rename it to named vehicles_airport.bgl, so you'll get the default file back. However, this will restore the default truck back on so, you might want to retry the installation, to be sure the file is patched properly.