Here's whats going on, I have a Zoom TAC-2 Thunderbolt Audio interface which I've been using for sometime with another macbook pro 17" and it had no problems on a macbook air either..

Just today I tried the interface on two different 17-inch macbook pros of mine (one running High Sierra the other is El Capitan and it appears to get no power from either of them. At this stage I was thinking okay this has to be either the thunderbolt cable or the Interface has died on me somehow. First I hooked one computer to the other in target disk mode to test the cable, no trouble getting target disk to do it's thing, but I went ahead and bought a genuine apple cable anyway just to be sure, still no signs of life from the interface.

Finally in a "there is no way this is going to work but what the heck" moment I tried hooking it up to my brothers same 2011 model macbook pro 17 and voilà, it does its usual LED streak up light. This made me happy but it still leaves a lot of questions about my 2 macbook pros and their thunderbolt ports.

Is it possible they're not providing power through the correct pins? The pins look clean to me so I don't see any obvious issue and the fact it works for target disk mode also seems strange. Anyone have any ideas of what to try or similar experiences not getting power from their thunderbolt ports? Could this be software even?

Thanks!