I have a rather complex fireplace, chimney, FP surround in place family that i am having trouble getting to display a split surface. I have split an area and painted a material to it. while editing the family the split and paint display as intended. When I finish editting, the split surface no longer remains visible. In an elevation it is visible, but the original surface pattern is also visible. In 3D view, the split surface pattern does not display at all - just the original pattern.

Anyone have any thoughts? TIA