Landscape Texture disappearing on Build


New to UE4, cant find any help on the net on this, so must ask what is surely a noob question.

When I assign a Material to the UE4 Landscape, it shows fine in the editor, but when I build the project, it does not show in the standalone. Only the default grey square grid. If I create a similar landscape externally (c4d) and import into UE, assign the same material and its working fine in the built standalone on a static mesh.

Can I please have some pointers and explanation of what is method to assign textures to the built in Landscape. I made it with a heightmap, but I assume that is no different.