How do lp refunds even work?

As far as I am aware, if you have a person running you down in game and you report them, you get your lp refunded (or at least some of it) if action is taken. I had a mid laner stealing my camps and invading enemy jg with me just to steal my camps so naturally the entire team reported him. A day later, I get the message that action was taken without actually getting an lp refund. Why are some forms of griefing instantly refundable while others aren’t? I didnt even get the new game termination feature thing.