Single player i have no issues using auto-aim. It won't work on mp, for a good reason
It was working on both yesterday, although on mp it was very glitchy. you would need to try aiming 3 or 4 times for a lock on.
But now, even in single player it wont do jack.
Starting to feel really disappointed in all this, I do hope it is all easy things to fix and mostly due to as always having crap servers (like every game ever made)