TROUBLESHOOT: video card is not seen in Ouputs Settings

If you don't see the video card anymore in your outputs settings, it may be that you are using a version of the driver that is not compatible with the version of that application. You should go to the product page and check the "Hardware and Specifications" area. There select the video card you are using and check which version of the driver is compatible with your software.

For example with OnTheAir Video, with a Blackmagic-Design device, you can see this here: 

https://softron.tv/products/play/ontheair-video?tab-content-id=specs-content

n some case, a video device is not seen even though it seems to be working fine and drivers are installed. The issue is most probably related to a security in macOS that require you to allow system extensions (kernel extensions or DriverKit) to load. And in some cases something goes wrong with this verification. All the information in these article: 

TROUBLESHOOTING: Drivers installed but video card not seen (Blackmagic-Design drivers 12.2 or later)