Screen sharing option missing from Ubuntu 18.04 (vino installed)

I have a computer on Ubuntu 18.04 (actually upgraded from Ubuntu Gnome 16.04). I need to set up screen sharing but the option isn't there.

In settings > sharing, the master sharing switch is on and I see computer name, but underneath that only Remote login and File sharing - no option for screen sharing as the docs suggest it should be.

As per the title, vino is installed - maybe there's another package I need that somehow didn't transition between the two versions?

This question is old, but here's an answer:

Log out, and then start the login (select your user name) but before you enter your password, click the gear-icon...then select the "Ubuntu with Xorg" and NOT the "Ubuntu" option.

Log in, and go back to Sharing...you should see "Screen Sharing" there now.

Screen sharing requires vino package installation per Ubuntu documentation.