This is affected by the Disney Infinity server shutdown of March 17, 2017.
Let It Go! was a Featured Toy Box in the Frozen Challenge and placed fourth place. It was made public on 1/2/14 and was created by MattMyx.
DISNEY INFINITY- Let It Go (Featured Toy Box)
Toy Box Description[]
"Find Queen Elsa on the anniversary of her coronation in this chilly Toy Box adventure."