I'm finding a similar problem with my project. I have a number of layers in a map with labels applied to numerous layers (i.e. road names, lot numbers, etc). I have World Hillshade half way down the list in my table of contents, with Linear Burn blending applied to the Hillshade layer. It was all working as expected, and still exports the layout to PDF correctly, but when I'm viewing the map view or layout view, all the layers above the hillshade have stopped displaying, making editing the map really annoying. As soon as I turn the hillshade off, or just turn the blending back to Normal, then it all works as it should.
I'm going to go with (another) bug, but I'll give it until Monday to be taught otherwise. If nobody has any tips for fixing this, I'll log (another) support request and update back here when I get an answer.
Lindsay Raabe
GIS Officer
Forest Products Commission WA