Error in vhost rebuild for subdomain

I am creating a subdomain of an addon domain.

The initial creation of the subdomain, from the users control panel, works fine.  I see the vhost.conf template filled in with the correct details, apache restarts and the subdomain works correctly.

However, if I do a 'rebuild vhosts' from the main panel, the IP address of the subdomain is missing from the vhosts.conf.

I see the following error above the panel that shows the vhost.conf:
Notice: Undefined index: ip_address in /usr/local/cwpsrv/htdocs/resources/admin/modules/vhost_rebuild.php(1) : eval()'d code(1) : eval()'d code on line 53

and so the VirtualHost directive comes out as:
<VirtualHost :80>

I can confirm that Rebuilding Virtual Hosts (vhost_rebuild) stops all subdomains from functioning.

This is a serious bug: