Windows still visible despite window rules

I use various Conky windows on the Desktop. Under rules, I have the following settings:

  • Window matching

    • Window class (application) - Exact match: conky
    • Match whole window class - Yes
    • Window types - All selected
    • Window title - Substring match: system_conky
      Above determined after running wmctrl -lG |grep -i conky. As well, the sub-string system_conky appears with ‘Toggle Present Windows (All Desktops):’ or ‘Show Desktop’ under each window.
  • Arrangement & Access

    • Keep below other windows - Force: Yes
    • Skip taskbar - Force: Yes
    • Skip pager - Force: Yes
    • Skip switcher - Force: Yes

When I use my shortcut of Meta+Tab to activate ‘Toggle Present Windows (All Desktops):’ Conky windows are still visible. Same for Meta+Ctrl+f8 to ‘Show Desktop’.

Is there a setting I am missing or is it not possible to prevent all windows from appearing?