[GAMEPLAY] Lissandra's E disappearing?

I found a visual bug on Lissandra. So sometimes when I play her, I'll use my e to farm (especially if I'm trying to push really quick). Sometimes when it hits one of the minions, the actual claw will disappear. The damage goes the full distance of the spell, however. This usually happens when I'm sitting in lane alone clearing waves. I don't know if it's just my computer, but it has happened more than once.