<?php

// add customer IP column header
function wc_csv_export_add_customer_ip_column_header( $column_headers ) { 
 
	$new_headers = array(
		'customer_ip' => 'customer_ip',
	);
 
	return array_merge( $column_headers, $new_headers );
}
add_filter( 'wc_customer_order_csv_export_order_headers', 'wc_csv_export_add_customer_ip_column_header' );

// add customer IP column data
function wc_csv_export_add_customer_ip_column_data( $order_data, $order, $csv_generator ) {
 
	$custom_data = array(
		'customer_ip' => $order->customer_ip_address,
	);
 
	$new_order_data = array();
	if ( isset( $csv_generator->order_format ) && ( 'default_one_row_per_item' == $csv_generator->order_format || 'legacy_one_row_per_item' == $csv_generator->order_format ) ) {
		foreach ( $order_data as $data ) {
			$new_order_data[] = array_merge( (array) $data, $custom_data );
		}
	} else {
		$new_order_data = array_merge( $order_data, $custom_data );
	}
	
	return $new_order_data;
}
add_filter( 'wc_customer_order_csv_export_order_row', 'wc_csv_export_add_customer_ip_column_data', 10, 3 );