Yesterday I recorded 30 minutes of my 720 and 1080i channels at HQ. I let them play last night on my 515H and there was nothing but perfect output upconverted to 1080p. These were all clear QAM if that matters, with bit rates from 4Mbs (ABC) to 8Mbs (CW, CBS & NBC).
I think it's likely the units are defective. But that's just my opinion - I could be wrong.