wp_get_nav_menu_items doesn’t return custom post type item

I fixed the problem by putting classes init in a wordpress hook wp_loaded as:

function instantiate_class() {
  FP_Nav();
  FP_Router();
}

add_action( 'wp_loaded', 'instantiate_class', 100 );

which is before the do_parse_request action and after my CPT init in the hook init.

I don’t know if it is the best way to handle this but it works well for now.