No surround Sound On Nvidia Shield

Im trialling Channels DVR on my Nvidia Shield TV but can't get anything but stereo even though shows are in DD 5.1 . If I use the HDHomerun app surround sound works but not on Channels DVR.
Please someone point me in the right direction, is there a setting somewhere on Channels DVR?

There is a setting under Playback but it should be on by default.