that is not a glitch or anything first u need to open your game and maximize it.Then press Alt and tab together and go to your desktop.Then right click on OBS and choose run as administrator then add a scene and in the sources choose game capture and right click on game capture and choose properties and in the mode tab select capture specific window.In the window tab choose your game and then click ok and click on start recording then immediately press Alt and tab together and go to your game.then when u check on OBS u should see the game in game capture
Hope it work...