Acquiring credentials assassin softlock?

I'm stuck on the part of acquiring credentials where you have to hit the cannonballs to send them back, I looked at some other threads about it and people replied saying that you have to use smoke bombs and time them well. But how on earth do you do it??

It's so incredibly frustrating to do as assassin, I remember easily doing this part with a mage profile but how are you meant to time the smoke bombs to hit the cannonballs?

 

I think just hitting them with a melee attack will work.

 

Yeah. Just melee attack them