Black Screen but Sometimes

[Xizan]

Hi i have a black screen problem but it happenes sometimes with some games. I can record some games anytime i want for example Arkham City. But some games like Arkham Knight or ETS2, sometimes i can record and sometimes without changing any settings it records black screen. I want to know this "sometimes", why this happening?

 

[Xizan]

It just happened now. Its recorded perfectly fine. Then i closed the game, opened it again, boom black screen.