I am following Blender Guru's mars tutorial and making a surface with rocks using two particle systems. One using bigger rocks and one using smaller rocks, both are collections of objects. The render result was fine at first but as I altered the rocks in the collection and made other changers, the smaller rocks disappear in the render. In the 3D viewport rendered view, it still looks fine, like this:
Does it has something to do with having two particle systems on one mesh? Because the plane in the back with only one particle system looks fine.