One of the types of Paint Layers that M4 uses is Overlays.

They are used for things like Foliage Removal, Layer Removal, Lightening/Darkening a layer, etc.

They are layers that can be used in combination or over top of other layers. A Layer within a Layer, basically.

Because of this, they need to have their Layer Info set as a “Non Weight-Blended Layer” when it is created for them. (See image to the right)

If you were to set it to the other option instead, it would just overwrite the paint layer underneath it completely, which we don’t want in this case.