Twitch ultimate bug

Hello, I am not sure if this is proper or not. I just played twitch for the first time in a while and I noticed when you're ulting you cannot damage turrets? Or inhibs for that matter.. I am not sure if this is how his ultimate is supposed to be, but its like I was attacking and the bolts were piercing the tower but only going through without doing damage. Maybe it was a single in game bug maybe its happening currently? Is this the way it is supposed to be or is this noticed by anyone else? Should be looked into.. thanks.