Glock, more info:
You posted that you don't use the Cinema DSP modes, but that's what gives the full 7.1.
Here's how mine is set in the setup menu:
Stereo/surround>movie
Manual setup>sound>Extended surround>PLIIx Movie
Manual setup>Option>decode mode>last
Manual setup>Option>extended surround>last
Now, when I have a soundtrack that displays PLII while in surround decode on the receiver, typical from SD channels on my cable box, I got 7.1.
But if I was watching a channel that displayed Dolby Digital on the receiver (HBO HD for example), or a DVD, the only way to get 7.1 is to press the "movie" button on the remote. This is what activates the decoder on the receiver for DD, DD+, DTS, TrueHD, etc. soundtracks to get 7.1. The problem was getting it to "stick" after turning off the receiver. Changing the settings I mentioned to "last" made them stick. Now when I turn the unit on, my last used settings are used. If I want to change from, for example, adventure to sci-fi or spectacle, I press the movie button on the remote which cycles through the different Cinema DSP modes.
Hope I explaind this ok for you. It can be somewhat confusing.
BTW, we watched Lord Of The Rings-Return Of The King last nite. That disc has DD+ex5.1. The disc played 7.1 with the receiver in surround decode mode. I didn't have to use the Cinema DSP to get 7.1.
HTH