When working with a decklink studio card in 5.1 surround, only the main aes stereo outputs are active unless you open the Blackmagic control panel and force it to run. (Just clicking on reset gain under audio levels without changing anything and the hitting 'ok' works). This then activates the other audio outputs and all is fine. I have to do this every time I start the computer it seems not all of the Blackmagic drivers start when the computer boots. This has been the same with all the driver updates, including 9.1.