TFT Glacial Fiora Bug

I just played a game of TFT running blademasters. I versed a glacial comp with a pyke and Fiora is supposed to stop spells and attacks with her ult. both the Ashe and Pyke ults(which are both spells) went through the fiora ult and she got stunned both times. If this is not a bug then fiora needs a buff or pyke/glacial needs a nerf. Please fix this.