Model not clickable, not walkable

[kokon]

I open a standard wall short model in reteras model studio. I save it at once.
I import it.

Now this model is not clickable and not walkable.
Recalculation of extents does not help. I don't get it.
Any ideas?

 

[kokon]

It seems it was fixed after i deleted LOD.
LOD is for performance? Can it be generated?