Vladamir Vs. Leona Bug with Vladamir's (W) and Leona's (R)

I just played a game as Leona and went to Ult Vladamir and he cast his (W) to go untargetable and when my ult came crashing down on him no damage was done to Vladamir. Ok so it looks like it's more than just Leona , Vladamir will take no damage from AoE at all when he uses his W.