I underwent the special event Chambers of the Statue this afternoon and completed it by looting the Moalith from the in game rewards mail. Tonight when I logged back in, I noticed it was gone. I play the game on 2 devices, and on the other game, everything is fine. I got the Moalith at the same time, doing the same steps and its still there.
Do you guys have any idea of what happened? 
I’m unable to repeat the quests again.
I’m sending an email to the support as we speak.