I have Garageband 10.1.6 running on a late 2012 MacBook Pro with Sierra. I watched this video: GBv10: Enable Multi-Track Recording - Minute GarageBand I followed the directions but I’m still having trouble arming two tracks at the same time. First, I set input and output to the 2i2. I then enabled two tracks: Track 1 is set to classic vocal. I then hit smart controls and information button next to master to connect to 1 2i2 USB. I then enabled Track 2 as microphone to use in front of my 12 string and connected to 2 2i2 USB. I try to hit both enable buttons and record but only one sticks. I’ve tried clicking the master record button before, then hitting both enable buttons.I tried clicking the enabled record buttons first, then the master record button — makes no difference. I am obviously receiving signals for both to the 2i2 but still can only have one source recording. What am I missing?