The [Install] section of the service file contains WantedBy=graphical.target however grahical.target is not a user target. Please change this in default.target (which is a systemd user target).

TIA

The current packaged version is outdated which means it's affected by this already solved bug: https://github.com/AppImage/AppImageKit/issues/642 (AppImageD ignores arguments in the Exec= line of the desktop file). I have found it out while downloading an AppImage with the parameter %U in the Exec key of the desktop file and letting AppImageD register it in the system. Whenever I manually modify the desktop file AppImageD detects the change and reinstalls the desktop file without the parameter.