Page thumbs not displaying in SL360 - bug?

Hi Chris, 

Sorry to hear that you ran into this behavior. 

Slides that are showing blank thumbnails usually indicate the presence of corrupted data. One troubleshooting step that you can try is to import your slides over to a new project file to see if this will help restore the missing thumbnails.

If the issue persists, and you've gone through the items listed in the first article that I shared with you, would you be willing to share a copy of your project file here or in private by opening a support case so we can take a look at what caused the thumbnails to disappear? We'll delete it when we're done testing!