ThunderBolt to SDI converters only seen in some software?

Thunderbolt to SDI converters only seen in some software?

For example, we have a Macintosh Studio, and have 3 thunderbolt to SDI converters, which Pro-presenter 7 sees just fine, we can assign screens to each of the three converters, and they are connected to our (BM) video hub, just fine.

However, Keynote on the Macintosh Studio can not see the BM 'screens' in fact the Macintosh OS only shows the one monitor connected (HDMI I believe), where we expected to see 4 screens total at the OS level. The BM Video Setup software and drivers are installed clearly work fine in that Pro-presenter sees them, but why not the Macintosh OS or other applications like Keynote?

Is there a way to get the Macintosh OS to see the BM 'screens', thus expected Keynote to see said screens as well?

No, this is not possible. The UltraStudios don't add extra screens, they add SDI Outputs that software can be written specifically to use. ProPresenter has these drivers, so does other software like vMix.

There are workarounds (for example screen capture and output via OBS etc), but to be honest, if you need plain Keynote output these devices aren't really the correct tool for the job.