Somehow, using the exact same setup, the reflections from my planar actor are completely swallowed up by Lumen. I “think” its Lumen, because deactivating it via the Eye thingy…
The reflections are back, but alas, the Lumen features of GI are gone, which worked completely fine in 5.7
I am stumped and dont know how to continue to have lumen enabled AND my planar reflections.
I tried to change the settings via the post process volume, but I only get SSR that look completely messed up;
Does somebody know maybe a fix or where I could start looking? I really wanted to try out Lumen Lite for my game and I very confused as to why Lumen is breaking my planar reflections (?).
I did some more testing in an empty 5.8 and empty 5.7 project. I am able to recreate the missing planar reflections and also get a few bugs when it comes to the planar actor:
Right is 5.7 and left is 5.8 and already can see issues.
I didnt chance anything except for placing a planar actor and the 5.8 version gets heavy flickering and a weird shadow in the reflection. 5.7 is completely fine.
And with a post process volume, unbound, only GI on Lumen and reflection on NONE:
Again, in 5.8, no planar reflection at all. I know that the reflection in 5.7 are from the planar actor due to the small distortion in the lower part, which can be corrected via ExtraFOV from the the planar actor.
Planar Reflections have always fought with Lumen Reflections, and in 5.8 the Lumen reflection pass seems to overwrite the planar result more aggressively. A few things worth testing:
In your Post Process Volume keep Global Illumination = Lumen but set Reflection Method = Screen Space or None, and confirm Project Settings > Rendering > Support global clip plane for Planar Reflections is still enabled after the upgrade (restart the editor after toggling).
Try r.Lumen.Reflections.Allow 0 in the console to confirm Lumen reflections are what’s hiding it.
The flicker and odd shadow inside the reflection often come from VSM or TSR handling the extra view - test r.Shadow.Virtual.Enable 0 or switch Anti-Aliasing to TAA.
On the Planar Reflection actor, check Screen Percentage and “Render Scene Two Sided”.
Since an empty 5.8 project reproduces it with defaults, this looks like a regression - a bug report with your 5.7 vs 5.8 repro would be worthwhile.
