I just went through a freaking nightmare after buying 11 of these mounts. I have two battle.net accounts and purchased them on one account then claimed the mount across both accounts. They started vanishing from my inventory and finally found out that Blizz didn't accept my purchase (thought someone was buying and selling mounts, i guess). I then had to purchase again but this time used each battle.net account to order mounts for the sub accounts and so far no problems. Fingers crossed!