This was not a feature of DMC4, you would still get hit off screen by enemies but there would be sound cues.
I remember this working, but the AI will try to move towards the camera and then attack. But if their attack already started and you move the camera away, they would still do the attack.
And I like this, I mean, I hate been hit by stuff I can't see. Specially in games with no GUARD button. NG you get hit by everything no matter what, that is why most people in NG try to move in a way so they can see all the enemies. MGR suffers for the same thing, but I think it could had been fixed by adding the MGS4 Circle Radar around the character, unless that is an upgrade to Raiden.