I'm assuming that you have found and used the Wiki for the HD HomeRun tuners:
https://wiki.jriver.com/index.php/TV_Tuners#HDHomeRunIf that doesn't help, there have been some threads with similar questions in the past, a search may find the answer. While I don't use a HD HomeRun Prime tuner, I know they depend on DLNA to find them, so that MC can use them, so my recent experience may help.
I have been unable for ages to get my Sony TV to show up in MC as a Dynamic Zone, as a DLNA Renderer. Other applications could see the TV and play to it. The TV could see MC Servers and play from them. But my MC installations refused to see the TV.
However, I reconfigured my network a couple of days ago, and this has finally allowed me to see the TV as a Dynamic Zone again. The problem appears to have been the WiFi connection strength to my TV, even though it was reported as Excellent and all other network functions worked on the TV. I could browse the internet from it, diagnostics said the WiFi was fine, etc. I now have an ethernet connection to the TV and it shows up under Playing Now as a Dynamic Zone. I'm still testing, and it is still a little flakey, but changing the network connection to the TV seems to have fixed the problem.
It could still have been something else, but my conclusion, at this stage, is that MC needs a good reliable network connection to find DLNA devices, query them for capabilities, and add them to the MC interface. The same issue would apply to HD HomeRun Prime tuners.
So, what sort of network connection from MC to the tuner do you have?
Any Wireless in the network path?
Could your network be improved?
