Is the projectile setup correctly?
Does the projectile mesh maybe have a pivot point that is not in the center causing it to look off center? Maybe the mesh is moved?
Does the bone name line up exactly? Check if your bone name has a space on the beginning or end, same thing for the passed name in the get socket location node (you can copy the socket name inside of the skeleton)
Unreal should add a return bool that could warn if the bone / socket is missing.