Ponycopter (Hecarim E bug)

Haven't had time to highlight the bug but I was playing Hecarim last night and I noticed once for sure that Hecarims E did 0 damage. The sheen proc off his E on towers tends to chunk quite a bit of health off a tower especially late game when built. Now I'm curious to go back and see if this effect happened more than once. Regardless I can post a highlight later since I was streaming of the E doing no damage to a tower. Riot please fix my favorite champion ;-;