Hipocrita.6357

I'm trying to complete the mistward armor set collection and the last piece is the Mistward Legguards, already done the Mark II golem 5 times and no drops, all the other world bosses of this collections dropped it in the first time, is this some bug? If so, how can it be fixed? Already partied up with other persons doing the same collection and they got the drop while I don't.