Hi - I've recording 2 tracks and want to record ThumbJam in a 3rd track. TJ is input, Auria Pro is output. The 3rd track is present and armed. When I hit play the volume indicators on tracks 1 and 2 function but no sound comes from the speaker on my iPad Pro or from the headphone jack. Same thing when I unarm track 3. Disconnect Audiobus and I have sound back. I've searched and just can't find an answer. I'm missing something obvious, I'm sure. Can someone help?