Update, 4/5/17, 6pm: The vendor has resolved the problems that were causing the document preview tool to not render files. If you continue to experience issues, please report them to us by submitting support request.
Some users may notice that the document preview may not be rendering the file in bCourses/Canvas. The vendor is aware of the issue and working to resolve it, see the Canvas Status page for more information: http://status.instructure.com/
In the meantime, you can still download files and open them locally on your desktop or mobile device.