Is the first time I notice this feature in options. I knew SF has a black list but I totally ignored KI had one.
But I can’t find the option to send anyone to the list 
Is it functional?
I think if you block them on Xbox Live then they’ll be blocked in KI. But it’s only from anything but ranked.
I’ve blocked few ppl, like really few (and not because of losing just to clarify) no one appears in that list.
Another KI mistery 
No that “block (LB)” in game is for blocking Steam players.