Blender 2.91 Cycles: Why is the render result different from the viewport rendered view?

Question

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:

but in the rendered result, there is like only 10% of the small rocks rendered. (Big rocks hided and material was adjusted to shrink the file size)

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.

Here is the file:

Answer 1

It seems like some of your rock visibilities are disabled in the Outliner. Click on the funnel icon and click on the camera icon to display the Disable in Renders option: