Particles hide other objects?

When I turn on particle system for plane,it hides other object(in my case it’s sky).These are two screenshots - without particles and with them.I think particles change culling of my scene.

with particles:

How to solve this problem?

I am pretty sure its not the particle problem but maybe some code surrounding. Look harder. Also render.ls() before sky vanish and render.ls() after sky vanish could give us some insight.