okay, here we go.
enemy hit player >> Player is " flash" in 1 second and can't be hit again during this time.
Just write a code like this:
Enemy overlapping Player
Player is "flashing" (right click on "player is flashing" and click (invert))
Invert mean the event only active when player isn't flashing :D, it'll solve your problem .
I'm added some "Health number" for player, so you can see, when flashing player never lose his health, but when flash ended, he will be hit again.