The forsaken attacked Rand before during the cleansing only because the DO ordered them to, and because Rand was distracted and could not use the CK against them. This time there was no such order (and infact the opposite in that Moridin ordered Rand to be kept alive) and as such the forsaken are not willing to risk their lives by challenging CK!Rand. And in truth if they had attacked, Rand would likely have annihilated them with ease.

So basically the standing orders from Moridin are that Rand is NOT to be hunted, and even if no such orders existed the forsaken would be too scared of dying to challenge someone wielding the CK unless they were forced to.