I can't link you to a more relevant source, so I'll just say that it's a specific glitch of this certain model that appears regardless of maximum object details set or not.
Though, it's a must do to see quite a lot of models here, so it's not debatable.
That's unfortunately just something that happens to the Heron. I flew one for a while, and there's not (to my knowledge) a great deal that can be done from this end.
On the upside, it gives you something interesting to look at.