Check out the patch notes for the v19 Winter Mischief update here: http://maplestory2.nexon.net/en/news/article/55464/winter-mischief-v19
- Last Active
This isn't a bug, the NPC is hidden. They can be found on the base of the top hat near the top(?) of the map, or if you want to make it easier for yourself go to the minimap settings in the top right corner and turn on friendly NPCs. They're invisible, so you'll need to walk around until the interact popup appears to find them.