Segfault launching Okular snap

I'm using Ubuntu 18.04.5 on x64 PC. Packaged version of Okular is too ancient for my needs, so I installed the newest Okular snap. Unfortunately, it crashes on launch. Here is the log:

paul@extra:~$ snap list
Name                             Version                Rev    Tracking         Publisher   Notes
core18                           20201210               1944   latest/stable    canonical✓  base
gnome-3-34-1804                  0+git.3556cb3          60     latest/stable/…  canonical✓  -
gnome-calculator                 3.38.0+git7.c840c69c   826    latest/stable/…  canonical✓  -
gnome-characters                 v3.34.0+git9.eeab5f2   570    latest/stable/…  canonical✓  -
gnome-logs                       3.34.0                 100    latest/stable/…  canonical✓  -
gnome-system-monitor             3.36.0-12-g35f88a56d7  148    latest/stable/…  canonical✓  -
gtk-common-themes                0.1-50-gf7627e4        1514   latest/stable/…  canonical✓  -
kde-frameworks-5-qt-5-14-core18  5.68.0                 4      latest/stable    kde✓        -
snapd                            2.48.2                 10707  latest/stable    canonical✓  snapd
paul@extra:~$ sudo snap install okular
okular 20.04.0 from KDE✓ installed
paul@extra:~$ okular
Qt: Session management error: Could not open network socket
Fontconfig warning: FcPattern object weight does not accept value [0 205)
Segmentation fault (core dumped)

Launching Okular from Gnome fails too. BTW, there are two Okular icons for some reason, both behaving the same:

I would appreciate any clues to resolve this problem.

EDIT

More system info as requested:

paul@extra:~$ which okular
/snap/bin/okular
paul@extra:~$ okular --version
Qt: Session management error: Could not open network socket
okular 1.10.0
paul@extra:~$ dpkg -l | grep -i okular
paul@extra:~$ apt list -a --installed okular*
Listing... Done
paul@extra:~$ 

The okular 1.10.0 version is surprising, since I was installing Okular snap, which is supposed to be v20.04.0.