So it is working then unless you hit them a second time? There's no mention of the invincibility thing in the screenshots. That trigger once you can remove it is redundant here and doesn't do much. If the problem is it is dying when it is meant to be invincible then need to see those events. Also waits are generally bad in functions, not sure if it's the problem here though, but you should remove the wait 0.1 seconds and replace the 2 second wait with a timer on the enemies and use on timer ended which is better.
"The outcome is: During the first hit, the enemy flashes but goes back into attacking/walking state & animation depending on the usual conditions for those states. During the second hit, the enemy fades while going back into attacking/walking state & animation."
So what are you expecting to happen if an enemy is hit while 'waiting for 2 seconds' and dies? Are they meant to be invincible while waiting? Not really understanding the game or the logic behind the waits.