On my healer character I completed my daily assignment of killing grim calaca's and never gave me the message that the assignment was complete or let me click on the Day 10 chest reward. When I went home to check on the status on the lodestone, it told me the assignment was complete and a green check mark was on the chest reward but I did not receive anything.
did you fight them in twin giants? That's the location it says you need to beat them in. I missed it myself till somebody pointed it out to me. I would go back and do that on that wizard just to make sure