B&D,
I have no idea whatsoever if this might be the problem, but I ran into a similar issue with a new Denon 2900.
It would not read the DVD-A p[ortion of DVD-A discs. Only the Dolby Digital portion.
I found that there was a setting in my menu that was for "Audio" and "Video", in an odd place.
I thought it was for setting the default player mode, but as it turned out it was for choosing between the Audio and Video portions in DVD-Audio discs.
Look around and see if yours has something like this, and see if it is set correctly.
I was just about ready to send the Denon back for repairs before someone here got me onto that setting.
Hope it helps.
TjB