I've just received 3 Lorwyn Eclipsed Alchemy packs in my mailbox (new set released today) and encountered an error while opening one : just got an empty error with no text and "OK" button.
When I check my inventory, I only got 2 rares and 4 uncos from this alchemy set (equivalent of 2 packs) and no pack left to open. One of the packs just disappeared!