I haven't used the volume material to create fog in a while, but the behaviour isn't what I remember. Maybe this is a bug.
When using a volume material, it can either be assigned globally (in the render setup) or locally to an object. The "On Surface" mode is quicker, but only works when the object containing the volume effect is seen from the outside. However, when setting it globally, it works no matter the camera placement. So far so good.
The other option is to use the "Inside Volume" setting, which is significantly slower (more than twice the render time in these examples!). It works as expected when set globally, albeit slow. It works when seen from outside the object when used locally. When seen from inside the object it does not render correctly! Afaik, it was previously possible to place the camera inside the volume, and render correct volume effects. Is this a bug??
It's also interesting to see the difference when applying noise. With "On Surface" the result looks... extremely poor. With "Inside Volume" it looks great. I remember it as being a lot more similar.
The scene here is a simple box (gray CRN PhysMat) with some holes in the roof, a daylight with CRN-sky, and an editable poly object containing the fog.
Win 11, CRN 9 HF1, Max2023