Material expression "FloatToUInt" can trigger a check() when input is invalid

UE - Rendering - Architecture - Materials - Mar 11, 2026

When a "Float to UInt" Expression is used in a Material Graph with a valid direct input connection that fails to evaluate, function UMaterialExpressionFloatToUInt::Compile() does not catch the input ...

Nanite Skeletal Mesh ignores Hidden Material Section flag

UE - Rendering - Features - Nanite - Mar 11, 2026

Unlike non-Nanite Skeletal Meshes, Nanite-enabled Skeletal Meshes do not correctly respond to the Show flag passed via ShowMaterialSection(). Consequently, the Isolate checkbox for material slots in ...

Rare crash when changing scalability settings rapidly

UE - Rendering - RHI - Mar 10, 2026

It seems like the code in RefreshSamplerStatesCallback() can overlap with FillUniformBuffer when it mutates the Wrap_WorldGroupSettings and Clamp_WorldGroupSettings FSharedSamplerState objects. Addi ...

Nanite culling breaks on scaled object with displacement when camera enters displacement area

UE - Rendering - Features - Nanite - Mar 9, 2026

Nanite tessellation, only supports calculating displacement in local space and everything gets scaled with the object scale, which is often undesirable. If the camera enters inside the area allocate ...

Clicking on the timeline to move the playhead of the Persona animation viewer does not move the playhead.

UE - Runtime - Animation - Mar 6, 2026

Scrubbing is the only way to move the playhead. ...

Having a block in layout before switching to overlay strategy affects the overlay output.

UE - Runtime - Mutable - Mar 5, 2026

Issue: If "Resizable" Layout Strategy contains a block, it will influence the "Overlay" Layout Strategy. Expected behavior: When using "Overlay" Layout Strategy, it should disregard whatever the "R ...

StateTree: While editing State Parameters or exposed properties of a Condition/Task, an ensure() fires when editing inputs of a Property Function bound to an array element

UE - AI - StateTree - Mar 5, 2026

Consider an array property that can be edited in the StateTree editor. This can be a State Parameter or an exposed property of a Condition or Task, for example. Each element of the array can be boun ...

Clear coat bottom normal does not seem to work properly with virtual textures

UE - Rendering - Features - Feb 26, 2026

Clear coat bottom normal does not seem to work properly with virtual textures. Different virtual textures plugged into the material's base color can yield different clearcoat bottom normal results. ...

STAT_StaticMeshTotalMemory increases after repeated loading and unloading of a level containing Nanite static meshes

UE - Rendering - Features - Nanite - Feb 26, 2026

The issue appears to be caused by a mismatch in the value returned by GetResourceSizeBytes(EResourceSizeMode::Exclusive) between InitResources() and ReleaseResources(). At InitResources(), the repo ...

Nanite displacement issue when using along non-uniform scaling

UE - Rendering - Features - Nanite - Feb 26, 2026

Nanite Tessellation displacement direction is incorrect for landscapes with non-uniform scales. It seems to use the normal from the unscaled landscape, which can result in the displacement causing t ...