If I connect an older MacBook Pro (2015 era) with a built-in HDMI port, it works perfectly.
However Desktop Video shows not signal received, and Media Express shows no signal. It even knows that it's a Blackmagic device. It shows the second display in Display settings, it will allow me to change the resolution, mirror it, etc. If I connect an M1 MacBook Air to the DeckLink, using either an Apple or a Belkin USB-C to HDMI adapter, as far as the Mac is concerned, everything is fine. I just installed a DeckLink Quad HDMI Recorder in a Mac Pro, running Big Sur 11.1, and Desktop Video 12.0 (just released yesterday… nice timing).
