Hey there, there is a bug where playing 'The Invitation' on Legendary will mark off 'Commencement' on the Legendary triumph. That makes players often skip a Legendary run of that mission, thinking it was done or not necessary. it can let players complete the triumph without any character getting their exotic. A character does not qualify for their campaign exotic reward unless they've done all 14 missions on Legendary for definite. So you will need to play Legendary Commencement on your Hunter and then check the Altar of Relativity on Kepler, where the exotic should be waiting.