akali not doing damage

I've noticed this sometimes, but akali's ult will either miss or just deal no damage to enemies directly in front of her. I just had her attacking a kassadin, 4 ultimates in a row (had seraphs on her), and no damage. I would assume his shielding was enough to prevent her AAs from taking into his health, but her ult should have taken him down. He had no items, and was being hit from behind (which seems like it may be involved in the bug, as she jumps behind people and often is backstabbing). She's already been nerfed, but if she's bugged and literally doing 0 damage against certain opponents (or in certain orientations) then it makes the ninja build pretty much worthless, unless you get a gold fully loaded kennen and/or zed (and even then, they would be better used in other builds if the akali is useless)