Yep. It's the new anti-cheat update. I know for a fact because I uninstalled my BattleEye to check and sure enough, while I could not play multiplayer because I disabled anti-cheat, I could see the game capture again. The anti-cheat compatibility hook in OBS Studio has not been updated to work with the new BattleEye software, and I really hope it gets fixed soon. I don't know who has the authority to implement this fix, but I would assume it's TaleWorlds.