Often videos uploaded to Telescope might have more than one audio track, but the proxy previews may end up having all the channels combined into one audio track.
While there is a property in the Video I-Piece configuration(com.northplains.ipiece.video.xml) named mapAllStreams that if set to True preserves the audio channels from the input to the output during the video transformation step, but this doesn't have any effect if there is only one channel, or more channels in a proprietary format.
Adobe Premier Pro embeds separate audio channels in one PCM audio track in which case FFMPEG used by the Transformation Platform, is unable to detect those separate channels or make a selection. You can check for multiple channels in a single PCM channel by opening the source video file in Adobe Premier Pro or the application you created the video in.
This is not a bug and the feature functions as designed for Telescope.