Forwarders disappear from the Cpanel doesn't always mean that they are lost

When there is change in ownership or when the ownership is lost, forwarders wont display properly. You may also notice that you wont be able to re-add them even. In such case either contact us or make sure that the subdomain or domain entry is there in /var/cpanel/users/username similar to "DNSx=sub.domain.com" where x is a numeric. I hope this helps.