Casting faded shadows on stuff based objects

[Wivex]

I've stumbled upon a problem with making my stuff based statues casting the same faded shadow as pawns and plants do. It works ok, unless my statues are made from stuff. Vanilla game having the same issue with plant pot made from stuff too, casting no shadow until the plant is growing there, meaning that plant is actually casting shadow, not pot. Any tips about it and is it solveable issue?