Changing per layer parameters in a layered material that writes to RVT can cause temporary visual corruption

UE - Rendering Architecture - Sep 12, 2025

When using a layered material that writes to a runtime virtual texture. Sometimes when modifying a layer parameter in the material instance editor. The cached material data in the runtime virtual ...

Enabling STATS causes RenderThread to wait for GPU

UE - Rendering Architecture - RHI - Sep 10, 2025

The licensee noticed that in Development builds, the Render thread times are suspiciously similar to GPU times, and the same thing happens when enabling FORCE_USE_STATS in Test configuration. The is ...

SkyLight Leaking does not affect reflections when the SkyLight is static but static lighting is disallowed

UE - Graphics Features - Sep 10, 2025

Reflections do not receive SkyLight leakage contribution from a static SkyLight when static lighting is disallowed. This is caused by the function UpdateSkyIrradianceGpuBuffer checking if the SkyLig ...

Mover character stuck continuously correcting movement after having a skeletal mesh as movement base

UE - Gameplay - Player Movement - Mover - Sep 8, 2025

Once a mover character has had a skeletal mesh set as its movement base, it appears to get stuck in a desynced state after moving to a static movement base. It is only when the character's movement ...

[AI] Failed check in UMassSpawnerSubsystem::DestroyEntities due to EntityManager still procesing

UE - AI - Mass - Sep 7, 2025

It crashed when unspawning an AI which will destroy its entity. Inside DestroyEntities "IsProcessing" is true, but when it breaks into the debugger, "ProcessingScopeCount" is 0 (so IsProcessing shou ...

ensure(PinHelpers::UnresolvedPins.Num() == 0); fails after undoing in the editor

UE - Framework - Blueprint Editor - Sep 6, 2025

The underlying cause is some edge case involving a math expression node, which does some perhaps naive things with a contained graph. ...

Crash when changing r.MaterialQualityLevel when FastGeo plugin enabled in cooked build

UE - World Creation - Worldbuilding Tools - Sep 5, 2025

The engine crashes when the r.MaterialQualityLevel is changed in a cooked game that uses the FastGeo Streaming Plugin. The crash doesn't repro with the same steps in Editor, just in a cooked build. ...

Some operations on material instances do not transmit over transactions.

UE - Virtual Production - Tools - Multi-user - Sep 5, 2025

Crash when calling SetState inside state machine OnUpdate

UE - Anim - Sep 5, 2025

The crash happens when SetState is called inside the function bound to OutputAnimationPose’s OnUpdate in the animation state. This way of using Set State node is the same as shown in the official do ...

Lumen Translucency lighting vs opaque mismatch is larger than expected

UE - Graphics Features - Lumen - Sep 5, 2025

The licensee's VFX team has been struggling with getting their Niagara systems with translucent materials to fit into the environments they are being used in. In a project with default settings, the ...