Jinx not criting at 80% crit chance

Late game with runnans, infinity and rapid fire cannon which equals 80% critical strike chance you can get like 3-6 sometimes even more auto attacks in a row without critting. I wasn´t able to replicate it in a custom game (unknown reason) like i was able to get like 3 not critting aa one after another but that can be the rng gods abandoning me or something. Just the other items i had bt, atkspeed boot and maw. And next game with my friend on jinx he had scimintar, bf and atkspeed boot. Im not sure if i was realy unlucky or something but of every 10 aa atleast 6 did not crit if not more.