Aim Assist Not working

My aim assist doesn't work. Before lvl 40 it worked good, I had my setting dialed in, I was doing good. then after hitting lvl 40, the next day, I had no aim assist. Its been like this for over a week now. Iv reset my controller settings and still nothing. the only time it works is in firing range. I cant play like this, the game is no fun anymore.....Im on Xbox.