[AR] Reflection Capture Sphere and Metal Materials don't work

Testing out the AR template in 4.19 preview 5. I’m attempting to use IBL lighting only by using an HDRI for both the skylight and the reflection capture probe. My diffuse materials properly respond to the skylight’s ambient lighting, but when I attempt metals, I get all black (indicating a failure to receive specular lighting from the reflection probe). I have the reflection source set to my cubemap, and the unreal preview window shows me great results. But when I deploy the AR scene to my iPhone X (or iphone 7), all my metals are black (unlike the editor preview which shows correct). Also, if i set editor preview window to high-end mobile, I see the same incorrect result. Switching back to SM5 shows correct results.

Can anyone suggest or help me understand what might be going on here?

------------------------ Steps to Reproduce: -----------------------------------------

To test this out, simply create a new scene via the AR template, and create a “mirror” material:
------| Material Params:
–| White (3 vector constant) to diffuse
–| Metalness to 1
–| Roughness to 0

Assign that material to whatever geometry the scene contains (like the default cone/sphere static meshes the template is configured for), or simply a static mesh sphere you add to the scene.

Assign the default HDRI in the engine content folder to a sphere reflection capture, configure to use cubemap instead of “captured scene”.

Assign the HDRI to the skylight as well (although that doesn’t matter for a metal).

Deploy to iOS phone and see only black materials.

Is it possible that baking light is necessary to fully connect the reflection cubemap to the lighting system? Even though in AR mode everything is movable with a static skylight?

Only way i’ve found to solve this when it happens is to delete both the skylight and the reflection actor, , build lighting, then re-add them. But I can find no clue as to what causes the lighting to stop working.

I encountered this the other day…apparently the reflection captures are scaled by a factor set by the indirect lighting. No bake = no contributions from reflection captures. I had to modify engine shader MobileBasePassPixel.usf to remove the IndirectIrradiance mutliplier since we are not using baked lighting in our project.

Hi Eric, I met the same problem here. Have you enabled the correct reflection effect on mobile after you modified the codes? and what about the performance? THX