Same thing happened to me a couple of days ago. I assumed this was because I've not yet reached the level the character starts to become available. But perhaps not?
Hi @happykook@Annie_C If you completed all seven days and beat the challenges, then you are entitled to receive Dachs. Maybe you missed one of the gift boxes during that week? I missed one and did not receive Dachs, but i took a screenshot of the last day and explained that I had beaten the challenge every day, within the 3 attempts allocated. I thankfully received the Dachs costume. Good luck and kind regards