I see that your scale is set to 0, 0, 0 in both of your blueprints - could you try setting it to 1, 1, 1 instead? They may be spawning so small that they’re invisible.
Apart from that, the only thing I can think of is that they are spawning, but are flying off in a random direction before you can see them. It’s a long shot, but video games can be strange sometimes 
Finally, try dragging off of the return pin of the spawn actor node and checking it - you should be able to see if your projectile exists and where it is there.