She is using the other spells listed such as Chain Lightning, but not Ice Storm, not even once has she used it. I aggro'ed the entire occupants of Castle Volkihar to see if I could force it out of her but that didn't work, I left her at the castle and waited several days to see if she would reset but she didn't, Wabbajack won't work on her since she's essential, so I'm all out of ideas.
If I was on PC I could fix her but I don't have that option, looking at her UESP talk page I know I am not the first to have this problen but it isn't listed under bugs. I know for fact she isn't using Icy Spear like someone on the talk page suggested because her spikes are half the size.
Hopefully someone here will have ideas.