When using Amplitube on my MacBook Pro (2017 with 4 Thunderbolt ports, macOS Mojave 10.14.4) with Stomp I/O, I am unable to get Amplitube to generate audio. The audio lights to the right of the Gain knob on the Stomp I/O show that Stomp I/O is getting a signal from my bass or guitar. But the Amplitube input indicators don't light up to show that it is receiving the input. And no audio is produced when I play my connected instrument.
The Mac does recognize the Stomp I/O. I have tried this with two Audio Midi configurations and neither one succeeds:
1) using Stomp I/O for the input and output, and connecting a headphone to the Stomp I/O headphone jack.
2) using Stomp I/O for input and built-in audio for output and connecting a headphone to the Mac.
I have also tried uninstalling and re-installing Amplitube.
There are two other scenarios that do work as expected:
1) Amplitube for iOS with Stomp I/O.
2) GarageBand for Mac with Stomp I/O (no Amplitube).