VFX not drawing on Mobile

I am using Niagara with 4.20.2, I have a few very basic VFX, each with a couple of basic emitters. One for low detail smoke from a fire, one for some white churn at the bottom of a waterfall.
However, when running on Mobile, nothing is visible where the emitters should be. When an emitter should be drawn, I often see some strange white flickering underneath my 3rd person character pawn.

I’m not sure if I’m missing some basic settings or rules for emitters on Mobile, but the behavior is pretty odd and I’ve not worked enough with VFX to really know where to look for the problem. Any help would be welcome.

Thanks

You need to build on Vulkan for android since Vulkan is supported with Niagara in UE4.22.