Describe the problem. Be as specific as possible!:
Completing the "A Tree For Every Day" quest for the 7th day in a row does not cause a "Christmas Tree Day 7" quest to appear, nor is the trophy for the event given out.
Days 1, 3, and 5 had the appropriate "Christmas Tree Day N" quest appear after the "A Tree For Every Day" was completed. The Day N quest is the one that gave the reward and stamped the participation book. Failure of "Christmas Tree Day 7" quest to appear means no AEE, no completed book, and no trophy.