Issues when opening or sending translation jobs with the Advanced Translation Editor when WP SiteURL is different from HomeURL

Overview of the issue

If your WordPress site has different values for the WordPress Address (Site URL) and Site Address (Home URL) options in Settings → General, it may conflict with features that depend on the REST API.

For example, the Advanced Translation Editor may not work as expected, and you will see 403 JavaScript errors on the browser console when you try to send or open a translation job.

Workaround

Before proceeding make a full backup of your site.

1. Open your theme functions.php file.
2. Add the following code snippet:

   add_filter( 'rest_url', 'wpmldp_replace_rest_url', 10, 4 );
   function wpmldp_replace_rest_url( $url, $path, $blog_id, $scheme ){
       //Get URL's
       $siteurl = get_site_url();
       $homeurl = get_home_url();
       //Replace 
       $url = str_replace($homeurl, $siteurl, $url);
       
       return $url;
   }