Kalista Rend Bug

Recently, I've had a Kalista game where I almost effectively doubled my DPS due to quite a major bug.

I'm not sure how it is triggered or started, but I know it is ceased by death, which appears to reset it and cause it to stop happening.

Essentially, whenever I kill a unit with Rend, my next auto-attack, for whatever reason, automatically procced Rend, consuming no mana or cooldown regardless of whether the enemy was killed, and still applied the damage and slow. I did not press Rend any of the times and to make sure I kept testing it for the duration I was still alive to witness this bug.

If videos are helpful I can try to get one up.