Voiceless Karthus Bug

This isn't very game changing to anything but there is a bug that i noticed that he doesn't say anything at all. I noticed this when i attempted to do some of the taunts while in AI and none of his quotes played for Walking, Taunting, or using Abilities. So far i don't know if anything triggers this it just happens automatically at the start of the game. The Deathsinger can't be a Deathsinger without his voice.