Hi, I recently came across and issue with a few machines recently upgraded to sierra that were refusing to open any type of file in preview and we tried everything we found on the internet. I came across a maintenance software with good reviews (and its free) and we let it run on all of the machines and it seemed to fix the issue. I just wanted to let everybody know that there is a fix if you need it.
Software @: http://www.titanium.free.fr/maintenance.html
