Since version 6.5.0, Breadcrumb NavXT uses the custom capability bcn_manage_options to grant access to, and allow updating settings on the Breadcrumb NavXT settings page. By default, Breadcrumb NavXT tries to add this capability to the administrator role. However, some setups do not have an administrator role, and require the bcn_manage_options capability to be assigned to the appropriate role on that site.

The following code, when placed in a site specific plugin, adds the bcn_manage_options to the role ROLE:

function my_bcn_manage_options_cap_adder()
{
    $role = get_role('ROLE');
    if($role instanceof \WP_Role && !role->has_cap('bcn_manage_options')
    {
        $role->add_cap('bcn_manage_options');
    }
}
add_action('admin_init', 'my_bcn_manage_options_cap_adder');

Simply swap ROLE for the name of the role that needs access to the Breadcrumb NavXT Settings page.

-John Havlik