Shifting Sands Delay [GAMEPLAY]

As I play Azir his 'e,' which is shifting sands, sometimes responds late or i get tired of pressing 'e' that I just give up. I'm wondering if this is an actually bug or is this delay apart of his gameplay because this spell is crucial for Azir's quick escape. For example, I place a sand soldier, then immediately use conquering sands, then I press 'e' multiple times to try to get shifting sands to work. I use this combo to close gaps, escape, or jus to get somewhere faster. This also happens pretty frequently.