All black capture on Mac OS on secondary monitor

[Slypenslyde]

I'm currently running Mac OS Catalina but this has plagued me since Mojave, I've just been too lazy to sign up for the forums.

If I try to capture a window on a secondary monitor, the only thing LiceCap captures is full black. I know it used to work 3-5 years ago because that's when I first started using LiceCap.

Capturing on my MacBook's display works fine. But if I plug in another monitor, I only get a solid black gif.