Random Black Mesh

Hey all,

So i’ve bought in a large-ish project, and the majority of it comes in fine, however this side of the project does not appear correctly. Their is a sort of diagonal line across the project, where objects inside of it, will appear darker than their identical neighbours. If i move this to the righthand side of the project, they will light up just fine, but tucked up in this corner it hates it.

Building lighting dosent change this unfortunatley, i had hoped it was just a lighting error.