I think I know what’s going on, now knowing your approach.
What’s “Projectile Shoot”? It should be an arrow component. That way your projectiles will already shoot at the direction where the player character’s facing. Can you show the Components window of your player character BP? Or wherever you set that variable, if it doesn’t represent a component.
If it is indeed an arrow component, does it rotate as expected? You can check by disabling the Hidden in Game option on the Details window while having the arrow component selected.