Hi Michael, I assumed too much...



so in this image I can successfully boolean diff the blue object from the magenta base object ( trim works equally well ) resulting in...



but when I try the same thing with cyan curve ( either boolean or trim ) it doesn't work. I've tried recreating ensuring symmetry so I'm not sure what I'm doing wrong...



lastly, I notice that viewing from the right results in same image as viewing from the left, but should I see cyan and not magenta line from the right ?

right view


left view