Unexplained "alopecia" spots with Scatter!

Hi everyone,
I have tried them all!
The only way to fill this hole in the scattering is by removing a large amount of polygons from the surface.
It is not related to the slope option, I checked.
There are no exclude/include.
And Why right there though? It is always there. Even if I clone the surface and I make some editing on it.
I don’t understand.
I attached two images, in the second one the render is on orto mode from top to show the entire “alopecia” spot.
Thank you!


Did you check how it looks from underneath? Maybe for some weird reason some of terrain vertex normals got flipped?

No flipped vertexes! I think it is related to polygons density. I don’t know.

Would it be possible for you to upload that terrain mesh? No need for assets, just faulty terrain, so someone could take a look at it and possibly figure out what’s going on.

For now I solved with optimize modifier on the surface. I will also upload the surface with the problem as soon as I can. Thanks!