I've had a Blackmagic Intensity HDMI card installed on the MacPro for a few weeks now. It's recognized and hooked up properly to my monitor, however, when I run Final Cut Pro and switch the playback to the Blackmagic out option, I get nothing on the monitor. I did get playback when I first installed it but the next time I opened FCP up, nothing. Tried a lot of options...thoughts?
Well...without having more detail about what formats you're using and what preset youre on. It sounds as if you're using a different preset and just changing the output to Intensity.
So I would start an entirely new sequence to test. When you select an easy setup for this sequence pick one that matches your Frame size and Frame rate. As an example, if you are using 1080i choose the Blackmagic 1080i5994 option....you can choose any of those with the codec you'd like (prores is easy). Once that's done...try putting that clip in the timeline again and see if it plays out.