Aatrox passive dysfunction (GAMEPLAY)

Excitement of Aatrox 7.5 gave me a chance to dust his wings off and run some life-steal. However, upon dying (even with the passive icon being displayed as active ) Aatrox remained vanquished on the floor.
It would be possible to recreate by simply dying, waiting for the passive CD to renew and die again. I retried to make sure I wasn't just tired; First game ( apologies I wasn't counting) Second game, I counted three occasions where the passive was ready, yet no resurrection - x Vayne, Garen, Poppy and 1x vs Garen 1x vs Syndra . both in quick succession to see if the passive was active, but happened the twice/three times throughout the game. My only notion is that the damage causing death may possibly be not direct from enemy; ie; Immolate from Sunfire Cape or excess magic damage from another source as it is clear that the passive does work in some cases.
Step 1; Death Step 2; Wait for CD and again Death Step 3; Repeat step's one through to two with different sources of damage..... I guess.
Why is this helpful to us and good for you?
As a Riot fan and LOL gamer, Aatrox lust for blood and demonic incursion onto my screen made me happy. His passive allowed us to tower dive, initiate fights and be an all round pain in the ass. However, it goes without saying; not having his passive work diminishes half the reason I enjoy him. ( and I'm sure I'm not the only one)
In the brief games just played the 'bug' lost myself lane presence, team fighting ability and left me worrying more about engaging in the enemy backline. Being a utility of Aatrox, it would be nice - if this is in fact a problem then it would be nice to have him playing smoothly.