[GAMEPLAY] Leona W not giving defenses after explosion

On Leona, the tooltip on her W states that the armor and magic resistances linger for 3 seconds after the W detonation. After playing a game with her, I've noticed that it does not give these defenses until later in the game. After doing some tests I've found that it does not matter what rank your W is. It only seems to give the defenses after the detonation later on into the game!

Thanks, SgtMadmonkey