Krampus Assassination Mission Not Showing up

Hi there, just wanted to let you know that I have been grinding for Krampus for the past few days trying to unlock his core. I even got the card and him to S Rank. The error I experienced was that it says the Assassination Mission is unlocked for him. However it does not show up in the list even though he is on S Rank now.
Is there a special way to unlock him and his Assassination mission, or is this just an error in the game?

This is a bug that will be addressed in the upcoming patch, thanks!