Quick answer: Construct 3 Particles rate not changing at runtime? Setting Rate via Set Property reads the value at next emission frame — instant change requires resetting the emitter.
Action Set Particle Rate fires but emission count stays the same for several seconds. The particle system uses cached rate per emission cycle.
Force Re-Sample
Particles plugin reads rate at emission step. To take effect immediately, set rate then call Restart — flushes the internal cache and applies the new rate.
Spawn Rate vs Initial Particles
Initial Particle Count is one-shot at start. Rate is continuous. Confusing them produces “rate doesn’t do anything” reports — check which property your event sets.
Lifetime Interaction
Visible particle density = rate × lifetime. Halving lifetime halves visible density without changing rate. Tune both when designing intensity.
Verifying
Triggering the action visibly increases / decreases emission within a frame or two of the change.
“Particle rate caches per cycle. Restart to apply instantly.”
For pulsing effects (heartbeat, breath), wire the rate to a sine wave and call Restart at extremes — cheap, expressive, no scripting.