Thank you for your response.
I am still confused. I may be wrong but why when I activate the DOF debug mode in the SDK I can see LOD numbers for jetways and ground vehicles for exemple but not for the the building itself? I noticed that for the Asobo airports and for a few airports from professionals creators that I bought.
You said you used to join multiple objects for the lowest LOD creation. How is it possible? Does it mean that if you have a car and a truck for your higher LOD level (so 2 objects), for your lowest LOD level you are going to merge those objects together and only have 1 object (Maybe not the best example)? Do you “kill”, turned off one object so?