[Chaoswarriorx]

Long story short – Lots of A/D converters, like the Canopus boxes I’ve seen this issue on before, won’t pass an audio signal w/out a video one to sync to. That’s why it works fine when you capture black video along with it, or video alone.
Just capture both audio and video, then ditch the video…
Not that satisfing of a solution, but it works…

CK