Champ Not Attacking Bug is Real

I've continued to see the bug where a champ will just stop attacking and/or moving, despite no apparent, legitimate reason. I've lost rounds, and sometimes therefore matches, because of this.

And, to be clear, this is not caused by Swordbreaker. There is no swordbreaker symbol over the victim, there is often no swordbreaker on the enemy team, and the champ generally stops moving as well.

And it's not a melee champ with his access to enemies blocked. The champ will often be in the clear and have a path, or standing right next to an enemy, or be ranged and with someone he could shoot.

Any other legit events that could cause this?