Hello, Bungie is aware that some players are having difficulties when using their ammo synthesis packs. Bungie is investigating this issue and will try to get this resolved as quickly as possible. In the meantime, make sure you have verified the following actions for your inventory: Make sure your consumable inventory isn't full, as "sitting on" many Ammo Synthesis stacks may have to do with the issue. If your consumable inventory is looking full, place some Ammo Synthesis stacks in your Vault to help prevent the above-mentioned issue. http://www.bungie.net/en/Help/Article/12282