Casting any summon won't work below the perion platform (Rooms 13-17). If a player has a summon already active before entering the fm entrance, it will stay until it expires or until it's used again in the designated area. Edit: they also work on the Christmas Tree
This is just a bug with the design of the Christmas Free Market Entrance, unless this is a major issue we will likely not decide to fix this and just wait until the regular Free Market Entrance returns. This is also the same issue that causes dropped items to not land on your character in some parts of the Christmas Free Market Entrance.
