Strange objects in render using vray

Hello, I am trying to render a scene with Vray but I continue to have these strange refelctions/objects appearing while rendering that I don’t have in the scene. How do I get rid of these?
Many thanks

Check the faces orientation and the groups.

They look like the backs of objects like bookcases and desks and stuff as seen through an exterior wall. Do you have any hidden objects in the scene?

Yes I do have some hidden objects, but even if I ‘‘unhide all’’ the problem remains

I don’t think V-Ray cares about SU settings like that. It’ll render whatever’s there even if you hide it in SU. (Maybe I’m wrong, though. I use V-Ray 6 a lot but never have anything hidden.)

But if that would be the problem then I wouldn’t see the strange white thing when I unhide everything… right?

Do you know what the correct orientation of faces means? White on the outside, blue on the inside. Have you checked the model, setting Monochrome Style?

I am not very familiar with the face orientation, how do I know which one is blue or white if I have a texture on the face?

You can find many other cases like this if you search the forum: