Unreal Engine Issues
Unreal Engine Issues
TOptional value changes in parent BP don't propagate to loaded child BPs
UE - Framework - Blueprint Editor - Oct 27, 2025Context TOptional<T> is a wrapping struct around a type, that lets the property have an set and unset state, in addition to the property's value when set. It is editor exposed: designers can open b ...
Lumen reflections break when the normals don't match the pixel depth information.
UE - Graphics Features - Lumen - Oct 23, 2025Lumen Reflections can leave black spots in chrome materials with strong normals. Also tested on UE 5.5, CL: 41545209 and UE 5.6, CL: 45232827 ...
World Position Offset invalidates Point Lights Entire Virtual Shadow Map Cache when light frustrum is only overlapping a small portion of the mesh
UE - Graphics Features - Oct 22, 2025When adding a spotlight to the scene it does not correctly use cached virtual shadow map pages when the spotlight overlaps a mesh using WPO. This can be most easily observed by entering 'Cached Pag ...
Body Setup of a Static Mesh with Simple Collision will pass validation, but removing it and using only a Complex collision and setting Collision Complexity "Use Complex as Simple" will fail validation: "Bone None requires at least one collision shape".
UE - Simulation - Gameplay - Oct 20, 2025Context: By default, Unreal Engine creates both simple and complex shapes, then, based on what the user wants (complex query versus simple query), the physics solver will use the corresponding shape ...
HZB Occlusion causes large stalls on the render thread
UE - Rendering Architecture - RHI - Oct 7, 2025HZB Occlusion causes large stalls (greater than 5ms seen) on the render thread due to an RHI flush. This is caused by the following code in FDynamicRHI::RHIMapStagingSurface_RenderThread which force ...
Incorrect Lumen Scene direct lighting when objects behind masked landscape
UE - Graphics Features - Lumen - Oct 5, 2025When objects are placed behind or beneath a masked landscape and r.Lumen.HardwareRayTracing.SurfaceCacheAlphaMasking is enabled, the direct light evaluation is incorrect. There are two workarounds, ...
TMatrix<T>::InverseFast() ensure when running URootMotionModifier_SkewWarp::WarpTranslation().
UE - Anim - Gameplay - Oct 3, 2025URootMotionModifier_SkewWarp::WarpTranslation() uses InverseFast() within a block of code that is only executed if DeltaTranslation is not nearly zero. The ToRootSyncSpace transform the code builds, ...
FNiagaraScalabilityManager incorrectly reactivates a NiagaraComponent that was deactivated by runtime user code
UE - Niagara - Scalability - Oct 1, 2025Context: The Niagara System is the primary tool to do visual effects inside Unreal. Niagara systems can be culled due to distance. Problem: Once a deactivated Niagara System is culled due to distan ...
Wrong density calculation in UBodySetup::CalculateMass
UE - Simulation - Core - Sep 29, 2025Wrong density calculation in UBodySetup::CalculateMass. The licensee has provided the following analysis and suggested fix: In UBodySetup::CalculateMass, the following code is present: // physical ...
Custom Depth range is different than Pixel Depth range
UE - Graphics Features - Sep 25, 2025Shaders that compare custom depth and pixel depth get wrong output values because the ranges are different. This error is most noticeable over large distances. The difference in ranges is due to t ...