Can't display Glow effects with CesiumSunSky (maybe a general question)

Development Asset Creation FX
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1

Hi,

i try to use Cesium plugin with Unreal Engine 4.26.
I have created a bullet with a glow material.

The glow effect is visible if i put the cesiumSunSky at midnight (or if i remove the CesiumSunSky)

glow_cesium_without_sky
glow_cesium_without_sky599×512 54.7 KB

But if i put the cesiumSunSky at 1 p.m. the glow effect disapear.
glow_cesium_sky

This is my material:

glow_material
glow_material691×600 60.7 KB

I suppose it is normal but how can i force my glow to be visible even with bright background ?
i have tried to quickly add a very simple Niagara effect in my scene with Cesium and CesiumSunSky, and it is not visible.
i do not have this problem with a basic scene without Cesium.