When the dev mode Scenery editor is opened on an airport project and the airport Asset loaded in the Editor, re-exporting a .GLTF from 3ds Max will trigger a partial rebuild of that .GLTF.
However, this automatic rebuild doesn't use the "Packages" folder but, instead, it exports in the "root" of the currently loaded Project, creating a duplicated package sub-folder there, containing all textures which were used on GLTF that was modified.
So, for example, assume the following Project structure:
myProject.XML PackageDefinitions\myPackageDefinitions\myPackageDefinition.XML PackageSources\myModelLib PackageSources\data\myAirport
A normal build would create the package in a "Packages" folder:
However, when a .GLTF gets in the PackageSources changes for any reason (even manually edit the .GLTF file to trigger a rebuild ), the automatic rebuild that gets triggered will create a NEW folder in the project root:
Which contains only an empty SCENERY folder (no .BGL, no .JSON files, etc. ), containing a TEXTURE folder with just the textures which were used in the modified .GLTF.
In addition to getting this duplicate folder, this slows down the first rebuild, because it's not reusing the .DDS in the Packages folder.