I have the same problem with “WordPress Seo Yoast” Plugin & iThemes Security latest Versions!
When i go to the sitemap “/sitemap_index.xml” url from the backend of WordPress Seo Yoast i will become the following error and the sitemap dont show correctly !!!
wp-content/plugins/better-wp-security/core/class-itsec-lockout.php on line 339
Hope for fast help, i have this problem on more then one site!
Regards
DS
