Welcome to the Candy Crush Saga Community
Do you have a question or need help with your game? Ask the Community.
Hi and welcome to the community,
Daily treat calendar is a bonus feature in the game. And like all other bonus features it is also not the permanent part of the game. There is no guarantee that it will always be there available in your game. It can simply go out of the game or may be replaced by any other bonus feature. It may also be unavailable due to some temporary issues and might return to you any time. Please do the standard troubleshooting process.
Log out, update your game application, Restart your device , clear cache/history if you are using browser and login again to check if it solves your issue.
I hope that it may return to you anytime soon.