When beginning work on a Cast QC task, it is important to first confirm proper player setup for the audio pass assigned.
The audio stream should be chosen automatically by the Netflix system when it registers the audio set up. If your system is connected to 5.1, a 5.1 audio stream will be served. When checking stereo, you will need to alter your audio output device to receive those channels only.
Within Asset QC, you can also confirm your audio stream selection within the reference player. Below is an example of a Cast QC stream serving 5.1 audio:
And here is an example of stereo audio being selected for playback: