Lux's Ult Does No Damage

For a few days now I've noticed that enemy champions will sometimes not take damage from Lux's ult. This occurs both when being hit directly and when brushing by it. In a single game, I hit a Garen twice directly with the ult, only to have it do no damage. There were also multiple instances where the shot should have hit and appeared to miss. I would appreciate it if you checked this out.