I have an explosion that plays several layers of a particle Effect made in Cascade. when I drag in the effect to the Editor the effect plays like it does in Cascade. However when I run the Editor - the GPU particle Layer does not display, though all the other Mesh Data layers display fine. So perhaps I have a setting checked for an optimization. Though I was doing Niagara tutorials a few weeks ago and the GPU particles seemed to display fine if I remember correctly.