Niagara fluids not visible in Lumen?

So, I’ve been working with the Niagara fluids from the 5.0 content examples, and I’m noting that they don’t actually appear to be visible in Lumen reflections. This alone isn’t that strange, I figured something as complex as real-time fluid simulation might not talk to RT that well initally, but it gets stranger.

I tested every sim, but the confusing ones are the 2DGasSmokeFire_CameraFacing, and the 3DLiquidDamBreak, and they behave very differenty: the 2D camera-aligned fire sim isn’t visible in lumen or other reflections beyond screen-space, but the path-tracer not only picks it up, but realistically propagates emissive lighting in real time. Hardware RT can access the path-tracer, but unlike other Niagara particles, it isn’t visible in lumen reflections.

The 3D liquid sims are also strange: they’re not visible in lumen reflections (in 5.0, I’ve tested them in _main builds that support translucent reflections and they work great), but they’re an unlit black color in the path-tracer. I believe this has less to do with Niagara and RT and more with the SingleLayerWater material, but I truly don’t know.

Has anyone else experimented with these effects? Would love to hear more, I am blown away by how powerful (and expensive) they are.

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