Can't unlock Dark Crusader after completing quest

[leopard2]

Retrieved the flayed skin, witnessed the 4 stigmas, fought Paladin's Burden boss, obtained Paladin Set, summoned Isaac for the Lightreaper fight in Upper Calrath...just beat the final boss of the game and no Dark Crusader class unlocked.
Any ideas? Is this a bug or did I miss something. I even followed the Wiki

[MasterZalm]

hmm, I got it once I beat the boss with Isaac.
Did you get the special edition? it automatically unlocks it for you anyway.

[Yves23]

you should have it after beating the light reaper . U were offline or online ?

[Daniel]

Pretty sure you summon Isaac to kill light reaper in upper calranth

[CrazyLamer]

Originally posted by leopard2:

Retrieved the flayed skin, witnessed the 4 stigmas, fought Paladin's Burden boss, obtained Paladin Set, summoned Isaac for the Lightreaper fight in Upper Calrath...just beat the final boss of the game and no Dark Crusader class unlocked.
Any ideas? Is this a bug or did I miss something. I even followed the Wiki

I'm pretty sure you need to be online while doing it, otherwise your char or the quest was bugged and you have to re-do it all over again.