If you performed a Refresh, there should be a folder called "Old Firefox Data" on your desktop containing all your previous profile files. I suggest you do this:

• Close Firefox and copy all the Old Firefox Data folder’s contents to your current profile folder. Overwrite any existing (probably newer) files in the new profile folder, and remove the ones that are not present in the old backed up profile folder on your desktop. That should completely restore your old profile, albeit with a new profile (folder) name only.

Note that you could also remove the entire contents of the new profile folder first and then copy the old data there, so that the active profile folder name (and its associated entry in the profiles.ini file in the parent folder of the profiles folder) is the only thing that will be different from the previous situation.

• See if you can start Firefox and if it works as before.

• If so, choose History > Clear Recent History, choose All in the drop-down and select Cookies, Cache and Offline Website Data, and click Clear now.

When at it, it may be good to check if there is a file called sessionstore.js in the root of the Old Firefox Data folder beforehand. If not or if this file is rather big (10+ MB), there may be some corruption in the session restore that could lead to high memory usage (although I have also seen this happening by loading just 1 Google doc.) Starting a new session in Firefox should fix that.

Could you report back?

Wait, but before I try all that out. Woudln't that just get me back exactly to the place where I started and where I was having trouble with Google Docs?

Ok, so I still tried the solution and it doesn't work. Even after restoring my old profile files, I'm still back at a blank Sync Page in Firefox.

At lest now, I can see the sync tabs from other devices, but I still can't see anything in the Sync Page.

jbmorgado said

Wait, but before I try all that out. Woudln't that just get me back exactly to the place where I started and where I was having trouble with Google Docs?

It would, except that you would also clear some content that might solve the memory issue.

Can you try refreshing the page using Ctrl+F5 when in about:preferences#sync as well as when in about:accounts?

Also make sure to allow 3rd party cookies, and check whether you are using a Gnome theme that you might need to disable or change.

This solved the problem.

The issue was with the Gnome Theme. For some reason all of the Arc Theme Maia hide the Sync Page. I don't rememebr if it was always like this or some new introduced issue, but anyway, changing to the Default theme now shows the Sync page.

Thank you.