If you have recently applied a firmware update to your iD22 or just plugged your iD22 in for the first time then you may notice that your Alt outputs (Outputs 3+4) not working correctly.
This appears to be caused by the unit not being properly rebooted after the update and therefore not allowing the on board DSP chip to fully reset.
To resolve this issue simply remove the power and USB of the iD22, wait a few moments and then plug them back in again. You should now have audio on outputs 3+4.
If you still don't have any audio on the alt outputs then check your routing in both the iD application and DAW to make sure that audio is definitely being sent to the outputs.