We have a Blackmagic DeckLink Quad HDMI PCIe capture card that hasn't worked on any of the new updates. I just installed version 27 today and all of my input sources show up as black screens. The last version of OBS to work with our card is 26.0.2. After every new update I revert back to this one.
Version 26.0.2 Log File
Version 27.0 Log File
Version 26.0.2 Log File
Version 27.0 Log File