Okay, nothing obvious in the Registry.
Also, as I expected really, creating a Zone with the same name as the DLNA Renderer shown in Windows Explorer, or its UUID, only created a normal Zone.
I can't see anything relevant in the "Service & Plug-ins > Media Network" item either, although there are lots of DLNA Searches and Notifies. Unless I actually use the TV as a Controller (and Renderer) to pull media from the MC DLNA Server, in which case I see activity using port 52100 against the DLNA Media Server, which is I believe the port the TV uses for DLNA. This was mostly Getting Content Directory and Device Description, and then thumbnail images, and finally video pieces as the TV played a movie. On the Library Server I saw lots of activity on port 52199, but it was just Gets for the DeviceDescription.xml and Service_LibraryService.xml files.
The Dynamic DLNA Zone still doesn't show up under Playing Now, even though the TV is playing the movie.
Nothing other than PCs show up under the "Drive & Devices > Explorer > Network" item, which is a shame as that might be an easy way to add a deleted Renderer back into MC.
I had a couple of virtual ethernet connections created by Hyper-V when I installed that. So I disabled those to see if they were interfering. But no change. I also had a "TAP-Windows Adapter V9" network connection. Disabled. No change.
But the TV, based on the IP Address, is querying the MC DLNA Server. See the attached image. The TV is 192.168.0.3. The MC Server is 192.168.0.10. Maybe using port 52100 is an issue? But then my Android phone is also using port 52100, as is the Controller on the MC Server. Hmmm, maybe the TV thinks it is only a Controller. But then acts as a Renderer when it pulls media to itself.
So this one goes back to JRiver. If a Dynamic Zone can be deleted from MC, it should be possible to add it back in. Windows seems fully aware of my Sony TV as a DLNA Renderer. It shows up in the Registry many times, when I search for the UUID.
Although I still intend to run AndrewFG's software against the TV to see if I can learn something fro that.