Sounds like we need to do some troubleshooting for you, Bridge Guy. That's not cool.

So when you are playing a disc on the BDP-83 through the multichannel analog connection to the 990, you sometimes don't get any center channel audio? Do you also end up with no surrounds? On the discs that don't have a center channel, do you have dialog at all?
I haven't tried it in a while, but I thought you could use the front panel input button and the up/down buttons to scroll through all the inputs, including 7.1 Direct. Am I remembering that incorrectly?