I wonder why that is? I have all the DLNA options unchecked on all PCs.
If you mean that you have "DLNA Server", "DLNA Renderer", and "DLNA Controller" unchecked under "Tools > Options >Media Network > Advanced" then you should be seeing anything that says "DLNA" at all. When you say right click on "Playing from" I assume that you mean "Playing Now", as I don't even see something called "Playing from", and "Delete Dynamic Libraries" in under the "Playing Now" right-click menu.
I am pretty convinced that MC doesn't clean up old Zones that have been created and then deleted, or Dynamic Zones that are found and then lost, perhaps due to changes on the device or in the network. So I think what you are seeing, the supposed ability to delete the "Main-PC (Generic DLNA)" Dynamic Library, is a symptom of that. I think the issue with cleaning up old Zones may be the reason that not all Zones are shown in your configuration.
In fact I now have a configuration just like yours, with a Player, Stereo, and Multichannel Zone on my Server, and just a Player Zone on my Client PC. I have also turned off al the DLNA components just like you. So I am purely using Tremote on my Client, just like you.
Only two Zones show up for the Server, "There" and "There: Stereo". So a similar situation to you. Earlier in the day, when I had the DLNA components turned on, I saw all three remote Zones. But not now.
I do think that deleting any Dynamic Zone, such as a Generic DLNA" Zones, can have detrimental effects on how well MC works with Zones. But I can't prove that. I'm not going to test that either in case it really screws things up. I couldn't get my TV to show up as a DLNA Renderer for ages, and I thought that it was because I may have previousy deleted its Dynamic Zones but couldn't prove that, then I thought it was because the TV was on a WiFi connection which wasn't the best (even though other DLNA Server saw the TV just fine), and finally I now believe that it was because I had extra Zones on my Server. When those extra Zones were removed, my TV showed up as a target DLNA Renderer immediately.
So it is very likely an issue with how MC is managing Zones.
Your experiment with the Intel NUC is interesting, and it may give you a way to "fix" your current issue, though I don't know if it will last.
Take a Library Backup from your Laptop and Restore it to your SurfacePro, but
only restore the Settings, and not the "Library and Playlist". Theoretically, the SurfacePro should then show both your Zones, just like the laptop does. You may need to tweak some settings on the SurfacePro after the restore, like the local Audio Device, but that may be easier than fixing this other issue.
Let us know how that goes.