4.9.6 cant add ‘manage_privacy_options’ capability

In 4.9.6, once a Privacy Policy page has been defined, currently only users with admin role can edit that page.

I’m using the following to supposedly allow ‘Editor’ role users to edit the page but this is not working, any ideas what I’m doing wrong?

function update_roles() {
	$editor_role = get_role( 'editor' );
	$editor_role->add_cap( 'manage_privacy_options' );
}
add_action( 'init', 'update_roles');

Thanks