So... I created a new mod. Created a world space.

Set LOD water height to 0. Default water height to 0.

Default land height is set to 8000.

Usable dimensions are set to 4096x4096.

No parent world space.

Not a small world.

I built up some land in heightmap editing.

And then I get a giant black spot right in the middle of my terrain.

Does anyone have any idea how to fix this?