Select a World in Game Mind Map and there should be setting in right column, if not add it by clicking arrows (or plus) icon at the bottom of that column.
I used to get black capture window after recording easily for no reason when I used OBS. Then my friend recommended Joyoshare Screen Recorder to me. It can record in 1080P with 60FPS as well but much more smoother. Now I always take it to record my WOW gaming skills and them upload them to YouTube. Maybe it could be useful to you as well. p.s. looks like this:
Have you checked the video resolution and fps? If you set too high, videos would become laggy easily. But I seldom use OBS cause sometimes it would lead to a black capture window. I use Joyoshare Screen Recorder now. It helps me capture gameplay in 1080p smoothly. Maybe you could give it a shot.
