I dont know if a setting iv emissed but when I spawn trees in with a pcg graph the LODs dont work as they do if it was just a standard static mesh, the distance before it changes from LOD0 to LOD1 is about 20x further.
Turns out if I change the meshes from instanced static mesh to foliage instanced static meshes the lod work as expected. Im assumming that ISM treat all meshes as 1 large mesh.
