No clue if it is related, but looking at the state diagram of MediaRecorder (https://developer.android.com/reference/android/media/MediaRecorder), there are many situations in which reset() seems to be called that reverts the object back to a pre-setAudioSource state (looks like that method part of the Initialize method of AudioStreamer class). Please note that AudioStreamer is a combo of MediaRecorder and AudioTrack.
From further testing, we have devices that the audio streamer falls apart after a few startplaying/stopplaying calls. Maybe it is the case the I am being to aggressive with it and it is reset.