The System Monitor that is pre-installed on Ubuntu 18.04 is installed via the snap package, not from the traditional apt repo. You can verify that by running snap list, the output should contain gnome-system-monitor.
The snap execution environment doesn't see any of the icons on your system (local or system-wide). So this is somewhat an expected behaviour.
As a workaround you may remove the snap applications by running
The System Monitor that is pre-installed on Ubuntu 18.04 is installed via the snap package, not from the traditional apt repo. You can verify that by running
snap list
, the output should containgnome-system-monitor
.The snap execution environment doesn't see any of the icons on your system (local or system-wide). So this is somewhat an expected behaviour.
As a workaround you may remove the snap applications by running
and install the traditional one by running