In Gnome, if you try to add a menu extension, it does not work. Even the Applications Menu already installed won't launch.
I also tried to install another extension menu, Arc Menu, it just won't install from the Gnome Extensions web site.
I tried anything I could think of... Turning off the extensions all together in the Tweak Tools. Turning them off and on one by one. Restarting several times Gnome Shell : ALT-F2 r.
I went in Dconf editor, tried to set it the extensions to default on and off...
No luck.
The Activities button is letting no one near its fortress.