Audio Bitrate is not reported for Dash Content

I have a requirement to measure total bit rate (including audio and video) for Dash contents. I have found that audio bitrate is reported as 0 always for Dash VOD and Live Contents. Video bitrate is properly detected. There is no issue with HLS or SS contents.

Below mentioned are the traces of the events from Roku for streamingSegment:
type(msg)=roSGNodeEvent        msg.getField()=streamingSegment             msg.getData()=<Component: roAssociativeArray> =
{
    segBitrateBps: 0
    segSequence: 26
    segStartTime: 78
    segUrl: "http://www.bok.net/dash/tears_of_steel/cleartext/audio/en/seg-26.m4f"
}
type(msg)=roSGNodeEvent        msg.getField()=streamingSegment             msg.getData()=<Component: roAssociativeArray> =
{
    segBitrateBps: 1929000
    segSequence: 26
    segStartTime: 78
    segUrl: "http://www.bok.net/dash/tears_of_steel/cleartext/video/4/seg-26.m4f"
}

Audio and video bitrates are part of different AdaptationSet in manifest file(http://www.bok.net/dash/tears_of_steel/ ... stream.mpd).

Please provide information on how we can extract Audio bitrate or is this a known issue with Roku Framework. Have validated this in Roku 7.6 production and 7.7 Beta.