Garageband input monitoring cuts out when inactive
Garageband 10.1.0
OS X 10.10.5
I use garageband as a headphone amp to learn songs and write parts. Track one is an amp modeler for the line-in, with my bass guitar plugged in. USB interface for both input (passive bass) and output (headphones)
Channel two is the song I am learning, mp3 file.
The problem I'm having: I have to hit the PLAY or RECORD button for input monitoring to work. I can stop the track and input monitoring keeps working as long as I continue playing. If I stop playing for more than 3 seconds, Garageband turns off my bass (like a noise gate, my bass' natural hum disappears suddenly). When I go to play again, I'm not hearing my bass. No input monitoring. It's still turned on @ the track. If I press play again, it returns. Repeat ad infinitum to learn a song.
How can I make input monitoring persistent? I need to listen some, play along some... then stop the track and play bass solo, write some notes down, play again, etc. It's extremely annoying to have to slam the space bar twice every time I want to hear my bass guitar in the app.
MacBook Pro with Retina display, OS X Yosemite (10.10.5), Time Warner Cable, 60 mbps/ 5 mbps