Cassiopeia invisable poison [Gameplay]

I just got out of a ranked game on the NA Server. The enemy team had a cassiopeia whose particles from her poisons were invisible to my team. This made it hard for the mid lane azir to lane against get. Since we can't see her poison we couldn't avoid it. My hopes is that this is looked at and riot will take some time to disable her to fix her bug or the player if this wasn't a in-game bug. THank-You for all the support and I hope a solution to this problem can be found. Have a great day!