The simplest scenario I have is with the 5 boxes next to "Select Time Period" in my screenshot. Z order affects how the issue occurs. If I change the z order on the large yellow box to the front, then you see what is in the screenshot. If I change the 5 boxes to be in front, then it covers part of the outline on the large yellow box instead. Either way, I have issues. The problems in the main grid are more random. However, each of those "cells" have many elements stacked on top of each other...each with unique visibility attributes.