[gibxxi]

Depecid, Onkyo Amps are known to occasionally "Lose" audio over HDMI, it's a known issue if you check their forums. Unplug the thing from the wall for 30 seconds, and plug it back in then try your audio over HDMI again, it may work. Onkyo issued a firmware update for the TX-NR515 (and others) that is supposed to fix the issue. Time will tell.

EDIT: Realised you were talking about TV input not the Amp, sorry. Anyhow i'll leave the message up for others.