Behaviour of particle shaders.

Greetings Unity people

I have some explosions happening in my scene, and they look great! but, when I add a little spot/point light in a little prefab, far far away from the place where the explosions are happening, the particles stop rendering as they were so far. The black smoke/dust particles start rendering on a white flat colour. If I disable that tiny little spot/point the particles go back to normal.

Any lead about why is this happening?

thanks.