I have an exterior wall made up of stacked elements. I've posted various problems with this wall over the last few months. Here's another one. My building is rectangular and has four corners. Two of them mitre perfectly, so I know it CAN work, but two of them somehow became overlapped and I cannot separate them. I've tried wall join, cut geometry. I've tried to pull then apart by aligning to reference planes. I've dragged shape handles and mystery blue dots that move without affecting the wall. This matters because I'm planning a high resolution rendering and this corner is right up front. This is what it looks like: