Two weeks later, this bug is still happening. It may even out overall, but I just lost a match because of it happening in a couple of crucial rounds.
And, to be clear, this isn't 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?