Sounds like a problem with the AVR. Contact Denon tech support.
Yes, I tried 3 different cables including a brand new monoprice ultra high speedI know that you said that it was working. But, I'm going to ask this question anyway. Are you sure that you have an Ultra High Speed HDMI cable between the AVR and TV?
If you need to, you can test your cable's capability using a hidden menu on the Denon AVR.