I have an issue with my scene, when i am using volume fog in environment, and subsurface scattering in materials on different models it looks like volume fog makes this models half invisible or multiplies the value visually, im not pretty sure how to explain this bug.
It’s working as it’s supposed to. If an object is sitting in a volume that has the same IOR, it becomes imperceptible. This video illustrates the concept.
The polymer balls have the same refractive and reflective index as the water. So when they are together the balls become invisible. The fog in your global volume material was acting in the same way. That is why your reflections weren’t visible and there were no refraction in your scene.