Obs lags out when game capturing league of legends

I can stream any other game (overwatch, tekken, etc.) with no issues with game capture but when I try to do the same with League it lags my game out so much. Constant frame drops it‘s not playable. I‘ve tried all sorts of solutions (run as administrator, check for updates, set up the screen from scratch, turn of nvidia shadowplay/overlay, disable game mode etc.) and for some reason I also can‘t window capture it? (Window capture doesnt lag it out but it‘s black screened instead). Is there a way for me to: either fix game capture for LoL or get window capture to not be black screened? (I tried borderless windowed, windowed and fullscreen mode) Thank you in advance.