Hello, that's a known problem. It comes from the mistakes in Noggit's code, I think. No one actually seems to fix it ever. I hope someone will have a look at it though, because even the most experienced worldbuilders suffer from this problem too. However, there is a way you can fix it I think. Try to change the terrain a bit on this place in Noggit. Use flattening tool to remove the crack, and, as a result, you will only have a small lines of dots which is not really possible to fix with the existing tools.
