Landscape Paint Smooth showing wrong layer?

Having a problem with Landscape Paint Smooth, shows wrong layer?

Screenshot 2023-04-16 185958

The Smooth seems to be a subtraction rather than a blend, it’s showing through to what was previously painted. As a test I’ve started with a base fill of the Mud layer but noticed when I need to remove there is no erase and is just painting over.

Kinda fixed it although not, using Alpha blend instead of Weight.