ViP612/622/722/722K DVR Support Forum
The problem is that the 722 has only the one OTA tuner, which is dedicated to TV1 when in dual user mode. I agree, that it would be nice if TV2 could at least see the OTA, even if it couldn't control it, but that's not the way it works.
The 722k (which I don't believe is shipping yet to...