Extensions not working at startup

I am using Ubuntu Groovy Gorilla. I installed this extension called floating dock https://extensions.gnome.org/extension/3730/floating-dock/ from gnome extensions. I turned it on and it worked fine and suddenly made my desktop look way better. But when I restarted Ubuntu, the extension doesnt work and I just see the standard ubuntu dock. When I looked at 'extensions', floating dock was turned on. The extension started working again when I turned off and then turned on floating dock. I noticed the same happens when I restart the gnome shell (alt+f2 r). Can someone explain what is happening? Is this the extensions problem or Ubuntu's?