Hey jaaw, All Legendary Engrams, as well as Rare Engrams, acquired from the new Fallen Public Event chests and the Crucible will not be recognized by the Cryptarch. You should hold on to all newly-acquired Engrams until May 19th to benefit from their upgraded decryption skill-set. More info can be found here: https://www.bungie.net/en/Forum/Post/121703802/0/0