Maokai Passive Bug

Occasionally during combat my passive did not heal me. Instead of the usual passive auto attack, my champ auto attacked normally. I was clearly lower than the threshold to proc the passive. This is the first time I've seen this happen. I was against a Jax which may have caused it. As it seems that when he uses his counter strike I can't use my passive on minions. I don't know how to put a replay of my game on here. But if you let me know how to, I'll add it; a good timestamp in the game is 27:00 and play out the fight. If you watch my champ's passive it shows that it is ready to activate, but when I auto it doesn't proc. This is pretty unfortunate and makes the champ unplayable as it defeats the champs purpose of being able to heal like crazy during team fights.