All viewports except Right appear to be empty

After performing some Solid>Difference operations which seemed to be fine; when I chose to turn off one layer (the layer of solids I’d offset for clearance operations which I was subtracting with) all of the viewports except the Right viewport went empty except for a couple of point objects.
Turning that layer back on had no effect. :fearful:

Edit: Here’s how I recovered the file:

  • I launched Rhino, selected New and used my usual template
  • Imported the file. Everything was still there :smiley: with the exception of Layer States :slightly_frowning_face:
  • Used Save As and gave the file a new name

I noticed in the process that a lot of layers had been turned off. What’s perplexing is that the Right viewport appeared normal.