[Gameplay] Kindred's W, Wolf's Frenzy, apparently does not count towards assists/kills

Had a game where I used Kindred's W against a fleeing Yasuo who was trying to execute himself under our tower. Wolf ran up and bit him, triggering his passive shields (and thus clearly doing damage). However, when the tower killed him, it still counted as an execute.

As far as I know any sort of damage, even if blocked by damage mitigation or shields or what-have-you, should still count as an assist/kill towards the death of an enemy champ. Possible bug specific to Kindred, or may warrant a look at the system if it's a bigger thing related to shields/mitigation.