Welcome to the forum!
First, I'm not sure which Onkyo setup you have, but I just went through this helping my boss with his setup. It was pure frustration until I realized that his Onkyo was doing pass through only, no switching, and we had no audio via HDMI.
We hooked up videio to the TV via HDMI, and audio to the receiver, both toslink and coax digital, and we were in business.