After switching to ActivityWatch v11, I’ve noticed that the icon on the menu bar didn’t appear, and that I couldn’t access my dashboard, even after restarting my computer. I am using Catalina 10.15.7 if it helps. I also have installed the firefox extension and cannot access the dashboard from here either (Firefox can’t establish a connection to the server at localhost:5600). I am considering reinstalling an older version but can’t get my hand on it.
Just realized that v10 was on github all along 
https://github.com/ActivityWatch/activitywatch/releases/tag/v0.10.0