Vel'Koz: Flash + E sometimes destroys his own E

As you can see in the video, flashing too early during Vel'Koz's E cast animation destroys the projectile, thus causing the circle it spawns to not erupt or deal damage. It's always E > Flash, not Flash > E, and the circle indicating where the projectile would land if it were to spawn always shows up. The timing is tight, it only bugs out if you flash in the first few moments of the cast time.