Wondering if anyone has found a solution to this? I'm having the same issue but unlike the OP, the cut plane shown on the face of my clip cube displays a section exactly as I would like to see it (like that shown above by James H.) however, when the viewport is created on a sheet layer, it displays as a solid rectangle. I naturally assumed that the creation of a section viewport from the clip cube would be WYSIWYG. I tried editing the section style to display a hatch instead of solid fill, and the viewport updates accordingly to a hatched rectangle, so clearly VW is treating it as a solid object. The fill attribute on my point cloud object is set to "none", so that's not the problem.