Yeah… I agree. Right now the game can delete any item without warning… or entire characters/stashes/ect… Even if it’s caused by a bug on blizzard they won’t restore any of the items. Here is what they told me.
For your cube, I’ve heard of others just doing the quest again and it drops. Hope that works, and hope you didn’t have anything in your cube when it went bye bye.
Play safe out there!