No HDMI extenders and short runs (6'+15'). I have tried all resolutions and turned off all bells and whistles on the X Box.

If I insert coupler where receiver is it works fine.

SEEMS IMPORTANT: As soon as I plug the game into the AVR I no longer get Volume and input (OSD) from the AVR, just "No signal" on the TV.

I have done dozens of these in the past with no issues. In fact I mocked up the exact receiver and display that went with this Xbox which was working before and now it will not.