I spoke to OPPO support and they were able to duplicate the no sound from the left front and right surround channels on the Top Gun BR. They said that they would be working on a firmware update, sometime in the future, to correct the problem.

OPPO stated that it appears to be an issue when using the MCA outs and the HDMI cable is connected directly to a TV. That's how I have mine setup right now. Soon to be changed since I ordered a PR-SC886P and it should be here this weekend.