The F117 is weird. Unless you already know what it looks like, any single view from any particular angle is quite hard even for a human to extrapolate from. If it wasn't in its dataset then I can forgive it that, particularly because the angular nature of it means that it could easily be tripped up into thinking it's not looking at an aircraft at all.

I'm not saying anything about the quality of the model here - just that the F117 is almost certainly going to be an unfair test.