I don't know if this helps, but I use an Intensity pro card and it supports 1080 i/p . Sorry to ask the obvious, but I assume you are using interlaced video and an interlaced sequence.
Yes, I use interlaced material (XDCAM HD 422 50i) and my sequence-setting in premiere CS6 is SONY XDCAM HD422 1080i/p
Not a BlackMagic user myself, but have helped set up a few systems. Besides Setup controls in Premiere, there is actually a separate panel with format/output options for BlackMagic, which I believe is found in Windows Control Panel. I forget what they call it. You would want the "1080i 59.94" setting. I think there is also a 60 option, but 59.94 is the right one (unless you are PAL user).
Safe Harbor Computers
The Sequenzsettings are SONY XDCAM HD422 1080i/p
That's confusing. Sequences can't be set to i/p. It's one or the other, so..which is yours?
@simon: This is an Adobe preset:
If I create a new Sequenz, I choose in CS6: "XDCAM HD 422 1080i25 (50i)" (Yes, PAL Area)
Then I can choose in "Settings": "Sony XDCAM HD422 1080i/p" and "25 Frames p/sec"
My Footage ist XDCAM HD 422 PAL with 50 interlaced pictures.
If I choose 50 Frames per second, the playback on the second HDMI PC-output is fine, but the Blackmagic did not work.
I can't find any adjustement for the interlace playback setting in Adobe Premiere CS 6 with the Blackmagic Decklink.
I have try every settings with the Blackmagic panel, but there is no change.
I got it :-)
right-click in the preview window: in german "Halbbilder" ( I think in the english version is it "Fields") then "Beide Felder" ("both fields"). I have thought, thats only for the preview window. This is also vor the playback with the Decklink card.