Primal Stalker (Purple) Lemix

Hey everyone,
my boyfriend and I just finished the Balance of Power questline together. Before that, we also ran a Mythic+30 in Lemix dungeon.

He got the Primal Stalker (Purple) , but didn’t get the “Keystone Master” achievement.
I, on the other hand, didn’t get the form at all, even though we completed everything together.

We’re both a bit confused — does anyone know why this might have happened or how to fix it?