Tessellation rotation issue + Heightmap artefact

Hello, I have 2 different issues on the same project / object.

I use UE 5.4.2 and followed the latest update regarding the tessellation. I applied it on an object and it was working just fine, but as I rotated it, it has become flat.

I have turned on/off the option “Always Evaluate World Position Offset” in “World Position Offset” inside the material, but for no change.

The second question is regarding the Heightmap: it works fine, but then it created an artefact on the top border, this:

image

I have already checked the size of all the textures: they are the same; and checked if the heightmap has a white line there: nothing found.

Does anyone know how to fix these? Thank you in advance!