I still have the original .pdn file. It opened prior to updating with all the layer information there.
It seems like the preview of the layer information disappeared. All I'm getting is the checkerboard background on the preview of all of the existing layers. The background preview has all the layers in it. But now it seems as though the individual layer information is still in the listed layers. When I turn off selected layers, I see the resultant change in the image. Pretty strange. I am just seeing a behaviour I wasn't expecting.