I was having the same problem. It may be a bug. My solution was to not use a plane with alpha. Instead, I modeled what I needed to see. It’s not the answer you’re hoping for, but there are a couple of other suggestions in that thread that you could try.
Particles are not detected by ray tracing, so they won’t show up in raytraced reflections or raytraces transparency, my advice is to always use Z transparency when refraction is not needed.