I'm trying to install Gnome Shell extensions from the Firefox plugin at Ubuntu 20.04. I followed all steps as described by this guide, but when I switch the install button to "on", nothing happens. The "download and install" window (as in step 10 of this guide) does not show and when I reload the page, the button says "off" again.
I have installed gnome-shell-extensions, chrome-gnome-shell and the Shell-Integration Firefox plugin. I have also re-logged in my session. Extensions are activated in the Tweaks and the Extensions Settings menu. I have tried several extensions. Any ideas what could prevent the "download and install" window to show up? Could it be related to the proxy I have to use to connect to the internet?