[GAMEPLAY] Tiamat's splash damage not working

In the following game, my (Fiora) Tiamat was not applying any splash damage: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2074841162/1?tab=overview

Around the 17:00 mark, if you can internally view replays, you'll see it. The active worked. Upon upgrading to Hydra, the splash damage worked properly.