Whenever I use a material in a particle effect it just becomes a square that looks like the original texture. I’ve gone through several tutorials hunting for something they’ve done that I haven’t that could cause this with no luck. I’ve also directly compared my work with free content looking for the same thing but still didnt find anything.
From my experience it was the post processing causing the issue. By turning the translucency from Ray Traced to Raster sorted it out for me.
Tell me the basic setup? Is it Niagara?