How do I fix this problem, PDF thumb nails are not appearing in the folders

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Ok so I just updated my Adobe DC reader, and the thumbnails are no longer showing.

In the folder explorer I have clicked view, large icons then clicked I clicked on the options, which opens the folder options window, there I clicked on view, and then clicked restore defaults, and still have the Icons, then I clicked on and made sure that the radio button is clicked and applied to Show hidden files folders and drives, as well as a tick in display file icon on thumb nails. The thumb nails still wont show.

So then I clicked on adobe Icon and went to and on the menu bar I clicked on Edit, general, and select as default PDF handler, then I ticked enable pdf thumbnail prewviews in windows explorer and clicked OK, and still the thumbnails wont show.

What am I doing wrong, or what is wrong with the system that it wont show the thumbnails.

Please help, as I have close to 2800 pdf"s that I need to see the cover pages to.

Thanks Brad

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System isa Windows 8.1 64 bit, and using Adobe DC reader.