Ubuntu 18.04 Software Center snap installation stuck at 99% (G.I.M.P.)

I was trying to install GIMP ("GNU Image Manipulation Program") to a Ubuntu 18.04 LTS computer, using only the provided user-friendly "Ubuntu Software" program; it seemed to be installing just fine, but then it reached 99% and stopped. I also installed OBS Studio and K4DirStat in this session. So, after 30 minutes stuck, I pressed the "Cancel" button, to no change.

I have never installed any program using anything other than the Software Center in this install, no apt-get, no .deb files. I heve never removed any software in this installation, nor have I cancelled any installation.

It only has a few programs installed: The ones that come with the system, K4DirStat, LibreOffice Base, OBS Studio, Firefox, VLC and PhotoScape.

This installation of the system is 2 months old, and mostly used only for internet browsing. It is the only system installed in this computer.

More technical information: the process "snapd" has been consistently using around 2% (1,7% ~ 2,7%) of CPU since the installation has been stuck at 99%. After cancelling, it stays using the same amount of CPU most of the time, except now it sometimes jumps to 4% briefly.

The snap list command outputs the exact same information running as both the "root" user or as the main user.

Output:

Name                     Version                     Rev    Tracking         Publisher          Notes
core                     16-2.47                     10126  latest/stable    canonical✓         core
core18                   20200724                    1885   latest/stable    canonical✓         base
firefox                  82.0-2                      440    latest/stable    mozilla✓           -
gimp                     2.10.20                     297    latest/stable    snapcrafters       -
gnome-3-26-1604          3.26.0.20200529             100    latest/stable/…  canonical✓         -
gnome-3-28-1804          3.28.0-19-g98f9e67.98f9e67  145    latest/stable    canonical✓         -
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        0.1-36-gc75f853             1506   latest/stable/…  canonical✓         -
kde-frameworks-5-core18  5.61.0                      32     latest/stable    kde✓               -
obs-studio               26.0.2                      1141   latest/stable    snapcrafters       -
photoscape               3.7-1                       43     latest/stable    merlijn-sebrechts  -
vlc                      3.0.11                      1700   latest/stable    videolan✓          -
wine-platform-5-stable   5.0.2                       10     latest/stable    mmtrt              -
wine-platform-runtime    v1.0                        179    latest/stable    mmtrt              -

It appears to have gimp listed, but the installation is still stuck, and "snapd" is still running.