Try putting on some music and switching to 7 channel stereo mode and see what happens. I recently thought the same after setting up my in laws 1910 last year. I only heard high frequencies coming from the speaker and it sounded odd. They have a very large room and the right rear is about 20 feet from the listening area. Then I realized audyssey sets the delay/level to be optimized for the listening position. At the center of the room where you sit, it sounded correct. Standing next to it, It sounded not right. Just to check, I turned on 7 channel stereo and the speaker sounded fine.
Possibility 2 is that the receiver is not handling the channels properly. I just recently had my 1910 get "confused" with Dolby digital. DTS HD & Dolby TrueHD were fine as was 2 channel stereo. DD would mix things up and my center channel would be misdirected but only when music played. Dialogue was still as it should be. Very strange. It happened with both directv and DVDs. Started after I was rerunning audyssey when I bought my new sub and it got stuck during setup. I did a microprocessor reset and it fixed the problem.
Good luck. Hope you get it figured out.