Have you tried version 8.5, some recent changes maybe germane.
IMO - the best solution is to not use the calibre viewer for non HTML based formats, I use Honeyview for CBZ and CBR, PDF xChange for PDFs, and WinDjView for DJVU.
To not use the calibre viewer for a format, and have it invoke the OS default, uncheck it in the Preferences->Behaviour->Use calibre viewer for: list. The formats I mentioned are unchecked by default.
BR
|