GameplayEffect not applied every time

Hello, I am trying to use Gameplay Ability System and I’ve set up Abylity System component to my player character and enemy character.

I’ve created sample skill:

Which waits for events from weapon:

And applies effect:

Everithing seems to be fine. Characters have their ability sets and abylity system components valid, animation is played, overlap event is triggered and all data is passed to ‘ApplygameplayEffectSpecToTarget’ call, but the effect (decreasing health) is sometimes not applied to targets and never applied on first hit.

Has anybody clue, what can be wrgon here?