Al did you ever get this resolved?
I think I have a similar problem. Disclaimer I am an amateur. I just got a Blackmagic Intensity Shuttle Thunderbolt and have problems when I try to capture composite video/audio. The Media Express software that came with it just shows a black screen. These are all of my home movies so there should not be any copy protection. I tried 2 vcr’s and 1 camcorder. These devices play fine in a tv monitor.
As a work around I have put the vcr’s/camcorder through a DVD player (composite) then into the Blackmagic and then I am able to capture fine.
Years ago I have captured these movies on DVD but I want to do it again to get the best quality transfer and of course make sure my Blackmagic is working.