I am having the same issue and have posted in the forums regarding this. The answer above does not apply as proven by my situation, because I have both a FireStudio Project and a StudioLive 16.4.2, which are daisy chained via FireWire. Same problem, except the difference is the Firestudio Project is recognized in my iMac's Audio/MIDI devices and Studio One 3... the StudioLive however is NOT showing up in the iMac's audio/MIDI settings nor is it showing up in Studio One 3. BOTH DEVICES are showing up in Universal Control and seem to work fine in just this one application. BOTH DEVICES are recognized under my hardware settings in the iMac. If the answer above was accurate to this situation, I should be able to plug in JUST the StudioLive and still have it show up in Studio One 3 as a FireStudio Project - this is not the case. When I have just the StudioLive connected, no external audio devices show up in Studio One 3. Let me know if you solve this. Thanks and good luck.