Hmmm, that’s not the intended behavior… 
You aren’t running in incognito or anything, are you?
We’re using the controls Emanuele mentioned, which means you’ll get the “Sign Up” overlay if we don’t recognize you. If you go from the editor to either this forum or our Community Projects page (both under the 
menu in the upper right), you should be able to view any project as before.
If this still doesn’t work for you, reply to your invite email and we’ll send you a fresh invite link to get you logged back in.