Show-Through AI

I recently downloaded a couple of AI aircraft that show-through other scenery. For example, if the aircraft taxies behind a hangar, you can still see the aircraft through the hangar. It looks like the aircraft is actually passing in front of the hangar, several feet in the air. The hangars involved are "advanced generic buildings", so there shouldn't be anything unusual about their texture. In any case, this only happens with these two AI.Anyone have an idea what's happening?Don