Actually, it does not work for my mechanic.
I need to keep "For Each" because I can have bigger enemies that overlap other enemies. Therefore, I use a variable that correspond to their Y position.
Like that, my characters can shoot the correct enemy because they are on the same Y.
I tried to remove for each and now, my characters shoot but their projectile pass through the enemy. Which is normal because they do not match their Y position anymore.
If I remove the variable for the Y position, the projectile will hit the enemy that is not on the same line but can overlap the Y position.
Anyway, I really believe that there is a bug because it does not make sense why "For Each" will impact the Spawning Event even if I put a Trigger Once.