Twitch and Challenging Smite

When Twitch is hit with challenging smite while going into stealth with ambush you have to wait the whole 6sec till you become invisible. This shouldn't happen until you receive damage and challenging smite doesn't apply any until hit with an auto-attack.

People involved: -Twitch -Volibear

Map: -Summoners Rift

Location(just to be more specific): -River between mid and bot lane