Why Niagara particles death(kill) immediately from switch gpu sim

This could be a very basic question. But I don’t understand.

  • Create ‘Niagara system’ from Contents Browser
  • And Select ‘Directional Burst’ Emitter
  • Dive to created NS, Click to Emitter, change the ‘Sim Target - GPUCompute Sim’ And check on ‘Fixed Bounds’

And then, the particle has only appeared in the first frame and has been confirmed to die immediately.

This is not what I intended. I just wanted to simulate it on the gpu.
What am I doing wrong?