Lumen HWRT Reflections of Masked Materials are incorrect when "r.Lumen.Reflections.HardwareRayTracing.Translucent.MaxRefractionBounces" is greater than 0. The same issue occurs if the Post-Process Volume setting "Lumen->Max Refraction Bounces" is used.
1. Download the attached test project and open.
2. Observe the three spheres, with striped opacity. Green is opaque, red is masked, and blue is translucent.
3. Observe the reflection of the masked sphere, and how it seems to brighten the sky in the areas masked away.
4. Move the camera to a grazing angle. (BugItGo -991.643430 -46.644761 17.915916 -4.642047 -717.764477 0.000009). Observe the double reflection on the masked sphere.
5. Observe neither of the two other spheres (Opaque and Translucent) have either behavior
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-358623 in the post.
| 0 |
| Component | UE - Graphics Features - Lumen |
|---|---|
| Affects Versions | 5.7 |
| Created | Dec 18, 2025 |
|---|---|
| Updated | Dec 19, 2025 |