Landscape grass ignores the scale of the parent actors

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.