I think it is probably something simple I'm missing but can you check this out for me? I have something rendering from Cinema 4D right now so I'm setting up particular for when it's done with an image.
I have created a ball luma matte that should have particular going around the ball in 3d space. But instead it shows all of it. There's a little explosion of particles that happens behind the ball so I know it showing through. If you look at these two images you will see the ball in in the center of the space with particular going around it. Then in the second image you will see the little explosion that is supposed to be happening behind.