I can watch TV fine with the HDhome run quick viewer. So I know the signal strength is good. I also switched back to the Microsoft mpeg2 decoder with no luck.
I have a hdhomerun prime that I just setup a few days ago. Below is what my decoders are set to and it works great for the most part. I've had a few bugs but I have worked around most of them.
[ATTACH=CONFIG]32033[/ATTACH]
Also not sure but did you select the right devices in npvr? I have attached my device list, and you can see that i had to use the ones labeled HDHR Prime, the rest of the SiliconDust ones I don't believe actually work. I got it working using what is enabled and didn't test beyond that. I have had a few instances where I get a blank screen and NPVR crashes, but typically restarting it and/or restarting the recording service has resolved the issues.