open the 64bit settings application using a rightclick on the shortcut and choose, 'Run as Administrator'
The above action will setup the thumbnails.
OR, select the [Reset All] button, this will also setup the thumbnailing.
The thumbnaling software also requires .NET Framework 4 to be installed.
This is installed automatically by Widows update.
Checking Control Panel | Programs and Features should show several Microsoft .NET Framework 4 entries