Niagara particle system partially working in custom event

Hello,

I made a niagara particle system that render small rocks in a shape, and they are not moving to simulate a static mesh. I added a boolean “Destroyed” so that when I activate the boolean, the gravity make the rocks crumble AND some FOG with it.

In my interaction blueprint, I fire a custom event that turn on the boolean when I press a key.

In my tests in playmode with my character, the rocks do crumble when i interact, but the fog doesn’t show up. If I turn on the boolean from the inspector directly, the fog does show up. If I turn on the boolean in BeginPlay or TickEvent, it does aswell. But no matter what I do, when i turn on the boolean from a “custom event” in my blueprint (interaction), only the rocks crumbling work, but the fog doesn’t.

Do you guys have any idea ? How does blueprint custom events work in background of this game engine ? Because it seems to be different than beginplay or tick event. I really don’t understand why the fog doesn’t show up in custom event…