I did a bit more testing with the supplied tvheadend. I notice Deinterlacing is not available when using your build, most likely because it is not using VAAPI anymore. Is there a work-around for this ? Watching Live TV without deinterlacing is something which is a deal-breaker (too) - even more so than the lack of HDR
I did the test on the NUC6 for this, which I never use before, so it is possible it is related to the NUC6 - rather than your build.