This issue has popped up in a number of Denon AVR threads across model years. A recent firmware update to DirecTV boxes is causing video issues most notably the loss of the OSD/GUI. Work arounds until DirecTV can issue a new update include: (1) connecting HDMI from the box to the TV with optical to the AVR, (2) connecting component/optical from the box to the AVR, or (3) setting NATIVE to OFF on the DTV box with a fixed resolution (eg. 1080i).
I would hope so considering there have been quite a few posts in various threads by Denon and other brand model owners who are in the same boat. If you haven't already, you should also call your DTV rep and complain as well. No clue as to when an update will be released. I'd order a couple optical cables from forum sponsor Monoprice so you have them on hand if needed as they come in handy HDMI handshake issues which are common especially with sat/cable boxes in general. In the meantime, if your DTV box has a coax digital output (most do), then you can connect a "yellow" composite video cable (part of red/white/yellow cable) from the orange coax digital output on the DTV box to one of the coax digital inputs on your AVR (see image below) and it will pass DD 5.1 just as an optical cable would at the same quality. To keep things familiar with your remote, if you are currently using the CBL/SAT source name for the DTV box, you can assign whichever coax digital input you use to CBL/SAT as well and then change the INPUT MODE setting to "Digital". When (and if, as you may not want to return to the old configuration) you reconnect the HDMI cable from the DTB box to the AVR, you want to remember to change the INPUT MODE setting back to "AUTO" or "HDMI".