Include this file or add this function to the functions.php file to fire the Facebook Pixel 'AddToCart' event on the 'woocommerce_after_cart' action.

facebook-for-woocommerce-overrides.php

<?php
// Add function to fix some for the event tracking issues from the facebook for WooCommerce 1.7.5 update.
add_action( 'woocommerce_init', 'wc_facebook_tracking_fixes' );
function wc_facebook_tracking_fixes(){
  // Get the facebook integration class.
  $facebook = WooCommerce::instance()->integrations->get_integrations()['facebookcommerce'];

  // Add add to cart event tracking to allow for WooCommerce redirect to cart after adding product.
  add_action('woocommerce_after_cart', array($facebook->events_tracker, 'inject_add_to_cart_event'));
}