I called apple support. They aren't aware of any known issues, but they did recognize that there were some discussions posted on the subject. The tech believed the issue was related to the order in which the audio initializes, based on a thread from one of the discussions out there. At any rate, this is what I did to work around the issue. I can't say with concrete evidence that it works for everyone, but it worked for me.
1. Unplug your Apple TV, Optical Cable and HDMI Cable
2. Plug in your Optical Cable
3. Plug in your Apple TV
4. Let the Apple TV initialize
5. Plug in your HDMI
For the time being this works, though not ideal. I would presume a firmware update is coming .. hope this works for you as well.