I had the same problem when I first received my Librem back in April. I did send a note to support in case others had this issue, but I reconstructed the scenario from memory here. I hope that helps you.
You may know this, but where I say to reinstall gnome-menus, use the --reinstall option on install. Otherwise, apt will not let you do it. E.g.
sudo apt --reinstall install gnome-menus