Thanks for the explanation Jonathon, it’s greatly appreciated.
I have a similar setup, except a MacPro with a Kona 3G card going SDI out into the Teranex and then Thunderbolt into a Mac Mini for capture. I have the BMD Teranex software installed and the Teranex is recognized by the Mac Mini, but whenever I have the Thunderbolt cable plugged in, it seems to cut off the SDI signal coming in. When I unplug it, I can see the signal without a problem. I’m on hold with BMD customer support right now and will update if I get this resolved.