menu is only pulling in one item

I have an issue where wordpress is only pulling in one menu item on a client's website... it was pulling them all in just fine until recently, so I'm not sure what changed.

This is how the menu was pulling in earlier, and it still does, but now only pulls in the last menu item...

<?php 
$args = array(
'menu_class' => 'sf-menu',        
'menu' => 'navigation'
);
wp_nav_menu( $args ); 
?>

Does anyone know what could be causing this or how to fix it?

Thanks