Nothing is "missing", all LOD are complete and correct, according to Asobo own official LOD diagnostic tool, which tells developers what is the correct LOD to use, based on their own calculation of the object size, the viewing distance and its polygon count, in order to prevent the simulator start removing objects that don't conform to the standard LOD rules, which GSX complies completely.
The issue is, the diagnostic tool is tuned to a "natural" viewing ratio, which in Drone/Showcase camera is a zoom of about 60-70, if you use wider settings, all distances change, meaning something that has been properly made according to those rules, will disappear earlier if a wider zoom is used.
This means, if we tried to make the objects visible at "any" zoom level, including the widest ones, we would end up creating "illegal" objects that won't give you ANY performance benefit due to LOD, because when you use more natural zoom levels, the sim will never get a chance to load the more fps-friendly LODs, since we had to set them for a wide zoom angle.
Then, there's the additional issue of "composite" objects, like Pushback trucks with a Toolbar ( and a driver ), which are in fact two objects combined, which give us the obvious benefit of using the same toolbar with different Trucks, instead of creating highly inefficient models containing the Truck, the Driver and the Toolbar, killing any chance for the sim to optimize them, because if you had a combination of those, if they were made as single objects, the memory footprint would be multiplied for each different variant, while now we are efficient as we can, because even if you have dozen of different toolbars linked to dozen of different tugs, the sim will only load one toolbar and would instance it with almost zero memory cost.
But this has some side effects that LODs of the object when used alone wouldn't be the same as LODs of the object used when it's linked to something else so, again, it's the usual compromise between visual quality and memory/fps efficiency.
Of course, we could just be sloppy, save a lot of work, make all objects with no LODs, so you'll be happy they'll never disappear, but we'll kill your performances and GSX would then started to be considered a "bad citizen", since it would take all the resources for itself, not allowing to use any other addon, which of course is wrong.
So, just accept the minor issue of not being able to use Wide angle zoom settings, which all considered is the best compromise.
