The previews of QuarkXPress documents are generated by a QuickLook file named QuarkXPress.qlgenerator. The previews would not be generated when the QuickLook version under Mac HDD > Library > QuickLook is 5.1 or less. QuarkXPress 2016 installs QuickLook version 5.1. But while updating the previous version i.e. QuarkXPress 2015, the current higher version of QuickLook file gets incorrectly replaced by lower version of the file.

You would need to manually install the QuickLook file. If you have QuarkXPress 2016 installer downloaded or you may also download it from the Quark website: and follow below steps:
  1. Open the QuarkXPress 2016 application
  2. Do not drag the QuarkXPress 2016 application to the applications folder.
  3. Double click on it and go to the 'For System' folder. In this folder is the “QuarkXPress.qlgenerator' file and copy it to the MAC HDD > Library > QuickLook folder.
  4. Now it's very important to change the permissions (Select the QuickLook folder > Invoke Press Cmd + I > Go to 'Sharing & Permissions' and click on the lock icon, enter admin credentials, and then select 'Apply to enclosed items...' under the settings icon).
  5. Restart the machine and launch QuarkXPress 2016 to verify its behavior.