Quick answer: Unreal Niagara event handler dropping events when event count exceeds buffer? Default event buffer is 1024 - increase via Stack Context overrides for high-volume emitters.

Particle collision events from a debris emitter exceed 1024 per frame. Only the first 1024 fire; the rest silently drop.

Increase event buffer size

System > Emitter Properties > Max Event Buffer Size = 4096 or higher. Memory cost is small; coverage is complete.

Or reduce event rate

Throttle event emission at the source. Collide-on-bounce instead of collide-every-frame eliminates 90% of events.

Monitor with stat niagara

stat niagara. Event buffer overflow events count; non-zero = dropping.

“Event buffers are bounded. Bounds visible in profiler; overflows silent in runtime.”

For high-event VFX, sample-only-recent events. Old events have less gameplay relevance; the buffer doesn't fill.