Bug#979507: okular: Okular fails to render markdown files

[Pavlos V <pavlosver@yahoo.gr>]

Package: okular
Version: 4:20.12.0-1
Severity: normal
X-Debbugs-Cc: pavlosver@yahoo.gr

Dear Maintainer,

On a freshly installed Debian Bullseye system, okular (with okular-extra-backends already installed), fails to correctly render markdown files, 
rendering them instead as plain text.

Using Plasma settings for file associations, okular appears to have been correctly set to use the text/markdown backend for such filetypes,
however when opening a markdown file in okular going to Help -> About Backend shows that the txt backend is used.

Thank you 

-- System Information:
Debian Release: bullseye/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.9.0-5-amd64 (SMP w/4 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages okular depends on:
ii  kinit                 5.77.0-2
ii  kio                   5.77.0-3
ii  libc6                 2.31-6
ii  libfreetype6          2.10.4+dfsg-1
ii  libjpeg62-turbo       1:2.0.5-2
ii  libkf5activities5     5.77.0-2
ii  libkf5archive5        5.77.0-2
ii  libkf5bookmarks5      5.77.0-2
ii  libkf5codecs5         5.77.0-2
ii  libkf5completion5     5.77.0-4
ii  libkf5configcore5     5.77.0-2
ii  libkf5configgui5      5.77.0-2
ii  libkf5configwidgets5  5.77.0-2
ii  libkf5coreaddons5     5.77.0-2
ii  libkf5crash5          5.77.0-2
ii  libkf5i18n5           5.77.0-2
ii  libkf5iconthemes5     5.77.0-2
ii  libkf5itemviews5      5.77.0-2
ii  libkf5jobwidgets5     5.77.0-2
ii  libkf5kexiv2-15.0.0   20.12.0-1
ii  libkf5kiocore5        5.77.0-3
ii  libkf5kiowidgets5     5.77.0-3
ii  libkf5parts5          5.77.0-2
ii  libkf5pty5            5.77.0-2
ii  libkf5purpose-bin     5.77.0-2
ii  libkf5purpose5        5.77.0-2
ii  libkf5service-bin     5.77.0-2
ii  libkf5service5        5.77.0-2
ii  libkf5textwidgets5    5.77.0-2
ii  libkf5wallet-bin      5.77.0-2
ii  libkf5wallet5         5.77.0-2
ii  libkf5widgetsaddons5  5.77.0-4
ii  libkf5windowsystem5   5.77.0-2
ii  libkf5xmlgui5         5.77.0-2
ii  libokular5core9       4:20.12.0-1
ii  libphonon4qt5-4       4:4.11.1-3
ii  libpoppler-qt5-1      20.09.0-3
ii  libqmobipocket2       4:20.12.0-1
ii  libqt5core5a          5.15.2+dfsg-2
ii  libqt5dbus5           5.15.2+dfsg-2
ii  libqt5gui5            5.15.2+dfsg-2
ii  libqt5printsupport5   5.15.2+dfsg-2
ii  libqt5svg5            5.15.2-2
ii  libqt5texttospeech5   5.15.2-2
ii  libqt5widgets5        5.15.2+dfsg-2
ii  libqt5xml5            5.15.2+dfsg-2
ii  libspectre1           0.2.9-1
ii  libstdc++6            10.2.1-3
ii  phonon4qt5            4:4.11.1-3
ii  zlib1g                1:1.2.11.dfsg-2

Versions of packages okular recommends:
ii  cups-bsd  2.3.3op1-4

Versions of packages okular suggests:
ii  ghostscript            9.53.3~dfsg-6
ii  okular-extra-backends  4:20.12.0-1
ii  poppler-data           0.4.10-1
pn  texlive-binaries       <none>
ii  unrar                  1:6.0.3-1

-- no debconf information