Hey guys,
To keep this spoiler free lets just say that you can use "Teleportation" or "Feather drop" (and aoe spells) at a certain point to reach something that would technically complete a quest, but does not.

details follow:

It's Icera the White Witch, if a player finds her before freeing the elements from Boreas staff, being able to remove her from the icicle prison with spells could be very confusing.

You are getting her out after all... she is just not interacting with you.