Because your first version used several "Start of layout" events.
In the end they were combined to be only one.
So it was like if you created instances, destroyed them, added some more, all in a row in a single tick.
Once again it is a matter of order and how events work.
Also in your current version, you don't need the event 3.
Just have an action "Pawn _ Destroy" in the event 2 (on Destroyer clicked) it will delete/apply to all instances of pawn.