Not seeing preview of thumbnail in Finder or if attaching to email

I have a MacBook and I used to see the thumbnail preview in Finder when I scanned in my documents.  Now I only see a blank icon with the file number which is very frustrating if you need to attach different documents to an email. Also even if I name the document it shows as a blank icon on Finder and when is blank when attached to the email. This problem started at the beginning of November when I upgraded my Adobe Acrobat Reader DC and also macOS Sierra 10.12.1. What should I do to get the preview of the thumbnail back?