I've noticed the same issue, but on the PS3 (which supposedly can decode DD+ to bitstream). Sometimes it works and sometimes it doesn't (even on the same show, movie, or episode). It doesn't reliably handle DD+. I wish I had a fix for you, but after working with both netflix and Sony, no one seems to be able to explain why DD+ is an issue. I've been in 2 channel mode for about 6 months now because of this issue.