I'm running Ableton Live 10 on 2015 Macbook Pro Retina (MacOS High Sierra - 10.13.4)
I intended to use an iRig HD 2 (1 In/2Out) and an iPhone 6 (0 In/2Out) running IDAM as input audio devices. I tried using an iOS app called Studiomux to avoid using IDAM (and to have a variable sample rate for the iPhone) but this failed miserably.
So I made an aggregate device - iRig + iPhone each at 44.1Khz - like you do.
When I select this aggregate as the input device in Live 10 not all inputs show as available. There are 2 mono inputs and one stereo input but only the iPhone device produces audio. FWIW, I can see 3 inputs if I select the aggregate device in Logic Pro X
So while Live was running I flipped the order of the sub devices in AUDIO/MIDI Setup. Of course this sent my system crazy so I rebooted and now when I relaunched Live 10 things had changed.
Now the iPhone has one mono input as does the iRig. ??????? Why can't I get a stereo out from the iPhone? Also to be noted both devices stopped working after some time.
Any ideas? Is this an Ableton problem or an Apple problem?