ZABBIX 2.4 on RHEL - Unable to add step to Web Monitor Scenario

Created: Application "Web checks" on "MicroStrategy Web Production".
preg_grep(): Compilation failed: range out of order in character class at offset 11 [httpconf.php:292 ? CFrontendApiWrapper->create() ? CApiWrapper->__call() ? CFrontendApiWrapper->callMethod() ? CApiWrapper->callMethod() ? CFrontendApiWrapper->callClientMethod() ? CLocalApiClient->callMethod() ? call_user_func_array() ? CHttpTest->create() ? CHttpTest->validateCreate() ? CHttpTest->checkSteps() ? preg_grep() in /wawa_mnt1/apache_httpd/httpd-2.2.31/htdocs/zabbix/include/classes/api/services/CHttpTest.php:650]
Web scenario step name should contain only printable characters.