Thumbnail preview of PDFs not displayed in the Explorer after updating Acrobat Reader DC to Feb 9, 2021 release
The thumbnail preview of PDFs is not displayed in the Explorer even though the Enable PDF thumbnail previews in Windows Explorer option is selected in Edit > Preferences > General.
Update your Acrobat DC and Acrobat Reader DC. The latest patch release (21.001.20142) has the fix for this problem. To update from within the product, open Acrobat or Acrobat Reader, and go to Help > Check for updates.