Bit depth / bevel aliasing when using custom SBSAR in Painter

Helllo!
I've created a custom material, importing it into painter and using it as a custom brush (a nuts and bolts generator) but I'm getting some major aliasing / bit depth artifacts in Painter where in Designer it looks fine. I've done various testing but cannot get rid of this artifacting at all. Does anyone know the issue here?

Thank you,
Marcus