devtrackers.gg
My friends were watching me stream over Discord, and it's very hard to tell. As far as we can tell, either the attack and projectiles are perfectly mirrored over each other and you cannot distinguish them, or it is not proccing while you stand still and attack.
Like other "also target" effects on strikes, such as Ancestral Call, the extra targets, regardless of being enemies or locaitons, must be a minimum distance from you to happen.