Since March, several users of Apple TV have experienced problems with getting Dolby Digital 5.1 from Netflix. Netflix has now acknowledged the issue and says that they will fix the issue soon.
Issue persists after 3 months
Since early March many users have been unable to output Dolby Digital 5.1 surround when watching Netflix on their Apple TV box. A later update temporarily fixed the issue, but the issue returned a few days later.
Netflix has now finally acknowledged the issue and says in a statement to 9to5mac.com: - We hope to have the fix out soon, but I cant commit to a date. We have put a workaround in place that will playback titles in stereo instead of Dolby Digital 5.1.
It is unclear if Apple has to issue a software update for Apple TV or if Netflix can fix the issue at their end without an update. No date for a fix has been provided.