If you mean that preview works inside Word for non-Word files, but not for
Word files, this is a known bug (actually, it seems to work at times, but
often not). The work-around is to use the preview in Windows File
Explorer... where Preview *does* work for Word files. I find that the same
bug exists inside Excel, as well... where Word files preview just fine, but
Excel files do not.
Some have found relief by disabling various add-ins, but I found that relief
to be short-lived.
