Context: this report comes from a RenderFuzz-based UE 5.5 rendering anomaly study. I am posting the issue publicly so other Unreal Engine developers can check whether it is reproducible, already known, or has a practical workaround.
I found several UE 5.5 captures where isolated colored spots appear or disappear
near lighting/reflection regions. They look like high-intensity magenta, green,
or blue spots rather than normal material animation.
Repro setup:
- UE 5.5 on Windows.
- Use the attached repro map and exact
conditions.json. - Static or slow-rotation camera.
- Inspect the lit/reflective region around the spot.
Observed result:
A small colored spot appears/disappears between frames even though the scene
lighting is not intentionally animated.
Expected result:
No isolated colored spot should appear unless it is produced by an actual light,
material, reflection, or post-process effect.
Evidence:
- Attach
evidence_sheets\04_光斑.jpg. - Attach comparison video and exact settings.
Question:
Which feature would you test first for this: bloom, lens flare, exposure,
translucency, or reflections? I am trying to narrow the smallest repro.
I also submitted this through the Unreal Engine Bug Submission Form and am using this thread to keep a public reproduction record.
Attachment note: I attempted to attach video_aligned.mp4 here, but this forum account is currently blocked by the forum’s new-user attachment restriction. The representative video was attached to the Unreal Engine Bug Submission Form submission and can be provided again when the forum allows attachments.