I can’t upload a header background image since upgrading, I link the image but it doesn’t show up.
Also the woo-commerce shopping cart has vanished, it shows up in the menu, but its impossible to access.
Have you tried clearing the Avada Cache files? Did you by any chance already try downloading a fresh copy of Avada and then completely replace the Avada template directory with a fresh copy?
I have had minor issues after upgrades in the past and one or both of these options has helped. I haven’t had an issue with the Avada template since I switch hosting companies though. To many hosts still use older versions of PHP because of the mass amounts of different websites they host on one server.