Woocommerce Action Filter for billing fields stopped working after V3 update

My functions.php customization for ordering billing fields stopped working after I updated to Woocommerce 3

This is the code:

add_filter("woocommerce_checkout_fields", "order_fields");

function order_fields($fields) {

$order = array( 
"billing_email", 
"billing_custom_field_10", 
"billing_first_name", 
"billing_last_name", 
"billing_birthdate", 
"billing_rg", 
"billing_cpf", 
"billing_custom_field_1", 
"billing_country", 
"billing_postcode", 
"billing_address_1", 
"billing_number", 
"billing_address_2", 
"billing_neighborhood", 
"billing_city", 
"billing_state", 
"billing_phone", 
"billing_cellphone", 
"billing_custom_field_1", 
"billing_custom_field_2", 
"billing_custom_field_5", 
"billing_custom_field_9" 

); 
foreach($order as $field) 
{ 
$ordered_fields[$field] = $fields["billing"][$field]; 
}

$fields["billing"] = $ordered_fields; 
return $fields;

} 

You can access https://loja.coexiste.com.br/ingresso (one page checkout) or try to buy any free product to see that the order is not working… (and breaking my css)

Any idea how can I fix this?

Tks in Advance