I've seen many threads with, hey 'x' has disappeared from my vault. Bungies answer is they will not replace missing items. It's not something that's happened to me thankfully but seeing as they track every button tap and joystick move they could surely see if an item had dropped for someone and it's missing due to a fault on they're end. And as for the server issues, there is no way in hell all other games work fine and only destiny has a problem and it's issues with our routers or consoles.