UE5 black shadow on seams between landscapes

Hey, I am just trying to generate a 40km100km2,5km map from Geodata and running into problems by importing the tiles. I use a tile size from 4033*4033 and import it one by one, but as soon as I enable “enable edit layers” I get this black seam only on the right side of the tile and I don’t know why or how to remove it without sculpting and overlapping.

I think my import data should be all right, I have the whole landscape in Blender as one model without any seams with a generate emissive Texture all over it for the heightmap and render it with a orthographic camera with the size of 40334033 and a resolution of 40334033 and move it after one tile to the next by script also about 4033 m first in the x-axis and than in the y-axis.

Before anyone is asking about the gap, I was rid of it before hand with the same data and don’t know why it is back now.

Because I just have geodata in a low resolution (50m between vertices on each axis) I also tried to scale down the resolution in the export to import all tiles at ones and scale them up in the editor. So I get rid of the seams, but I don’t get the water system to work with a scaled landscape.

Did anyone know a solution for getting rid of the seam or a better approach for importing the map in Unreal? Or how to fix the water system on a scaled landscape or to use it without to enable edit layers?

Thank you for your answers

Did you find any solution?
I’m having same issue with black landscape edges in UE5.1 and UE5.2 Preview.
UE5.0 does not have this issue.

It looks like that normals of landscape edges are calculated badly.

You could be trying to use the old landscape system instead of the new thing.

With world composition - the one that works in tiles - landscape layers aren’t supported.

With the new system they could be - haven’t really tried it so not sure.