SUMMARY
The print preview feature doesn't work in okular 1.11.1, it displays a blank page instead a preview of the print.
I use archlinux.

STEPS TO REPRODUCE
1. Install okular 1.11.1 and the last version of Qt5 5.15.1
2. Open a PDF document
3. Then click on the menu "file, print preview"

OBSERVED RESULT
I see a blank page

EXPECTED RESULT
I should see the preview of the print

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Archlinux, plasma 5.19.5
(available in About System)
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.15.1

ADDITIONAL INFORMATION
When running from the console I can see the error messages when I click on the menu "file, print preview" :

$  okular
ATTENTION: default value of option vblank_mode overridden by environment.
Settings::instance called after the first use - ignoring
**** Unable to open the initial device, quitting.
(libspectre) ghostscript reports: fatal internal error -100org.kde.okular.generators.spectre: Generated image does not match wanted size: [0x0] vs requested [574x812]
QImage::scaled: Image is a null image
**** Unable to open the initial device, quitting.
(libspectre) ghostscript reports: fatal internal error -100org.kde.okular.generators.spectre: Generated image does not match wanted size: [0x0] vs requested [557x788]
QImage::scaled: Image is a null image
**** Unable to open the initial device, quitting.
(libspectre) ghostscript reports: fatal internal error -100org.kde.okular.generators.spectre: Generated image does not match wanted size: [0x0] vs requested [80x113]
QImage::scaled: Image is a null image
**** Unable to open the initial device, quitting.
(libspectre) ghostscript reports: fatal internal error -100org.kde.okular.generators.spectre: Generated image does not match wanted size: [0x0] vs requested [557x788]
QImage::scaled: Image is a null image