Blending Landscape layers

So far I checked that for my class both CanAffectHeightmap() and CanAffectWeightmap() returns true;

My class implements both methods:
virtual bool AffectsHeightmap() const override { return true; }
virtual bool AffectsWeightmap() const override { return true; }

But still RenderLayer_Implementation is called once with InParameters.LayerType=0