DrawScale = Landscape->GetRootComponent()->GetRelativeScale3D();
DrawScale = Landscape->GetActorScale3D();
Changing as above will solve the problem.
Output log displays this warning:
LogPhysics: Warning: UpdateBodyScale: Unimplemented ImplicitObject of type: 4 skipped.
1. open NewWorld.umap
2. change the scale of the Cube
3. change the Grass Density of NewLandscapeGrassType.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-102930 in the post.