Unwanted Plane

Recently my boss was working on a file that has a block instance in it. When the view port is rendered or shaded there appears to be a plane right on the block instance obscuring half of it. We checked all the blocks that are being referenced in the file and we can’t find anything that is causing it. We copied everything to a new Rhino file and that took care of it but today I opened a different file and am having the same issue. Does anyone know what is causing this so it can be prevented instead of resorting to have to copy everything to a new file.

This is a view from above the suface.

And this is from below.

Hello - is the Ground Plane enabled in this file? (Ground plane panel from the Panels menu)


Yes it was. Thanks.