I have got the key for a while, I have finished the quests to gather crystals to open tower inner door and went on to other quests after that. A few hours later I want to go back to the tower to return black shards, however the key is no in my town hall vault. Given that the main quest key cannot be sold/dropped or stored into some random chest/barrel/body (verified with an earlier save), the only places it could appear are vault and backpack, but I can't find it in either place. Is this a potential bug or am I missing something?
