Now that we established that the version posted has the fix in question after all, we just need to figure out why this particular case is still problematic.
My thinking is that it's a plain old multi-cast issue. The simple steps to troubleshoot are to make sure multi-cast is enabled on the target network by pinging 188.8.131.52 as is is outlined in the FAQ. Most routers do not turn on multicast by default.
FYI, the difference between the old and new APIs is that we now always peform a multi-cast when the port number is not specified. The port number was added to the address in v2007.1 to support multiple WT servers on a given host.
I forgot where we left off with this prior to NAB. My opinion, is that what used to work, got broken in API 2007.1 providing me customers with a less appealing solution. As a recap, Wiretap 1.7 servers are not auto-discovered unless Internal DNS is running, which most places do not have. I have tested the networks and it is fine, multi-cast pings properly, and Wiretap 2007 servers are auto-discovered as expected.