The building you referred to was not a calendar reward - Buildings come in different categories with their own limits etc- If they made a new database item with the same characteristics, and they forget to mark it correctly as a star menu item, this is the result
So programming error
Not some deep dark conspiracy at BB to make life miserable for players
and yet again that word "Critical" Really get over yourself- this is an annoying irritating lamentable bug, but by no means a critical bug
It impacts a gift from the calendar - a decent gift unlike some others-
Chances are they will fix it as they fixed similar issues in the past Those that got hot will have to hope support will fix it, others can take this into account and avoid it