Material slot assignment incorrect after mesh reduction completely removes all triangles from a section

When mesh reduction results in a section becoming empty, the material slots are incorrectly assigned. e.g. if section 0 gets removed due to it having no triangles after reduction, then its material ...

Deferring Blueprint CDO construction at load time is leading to some data loss.

UE - Gameplay - Blueprint - Jan 27, 2023

Various licensees are reporting data loss on load due to the change that was made for [Link Removed] in which we now defer Blueprint CDO construction on load until the finalization phase. This issu ...

UKismetArrayLibrary::GenericArray_Shuffle is weighted to return some results more than others

UE - Gameplay - Aug 15, 2017

The implementation of UKismetArrayLibrary::GenericArray_Shuffle() will generate certain array shuffle results more often (up to three times as much) than others, rather than having a roughly equal c ...

[CrashReport] ULevel::GetWorldSettings() - UMaterialInstanceThumbnailRenderer::Draw

Tools - Aug 29, 2017

This is a common assertion that has occurred since at least 4.14 and affected nearly 100 users. The callstack is similar to [Link Removed], which was marked fixed for 4.14. User DescriptionsUndoi ...

Physics replicates incorrectly on the Client-Side on sloped surfaces

UE - Simulation - Physics - Jul 30, 2019

Replicated objects don't behave correctly on the client-side on slopes when not sleeping. By placing two cubes on one another and slightly rotating the bottom one to create a very gentle slope, the ...

Connection to dedicated server no longer works on iOS devices

UE - Networking - Oct 11, 2019

"Looks like the cause of this is commit fb473a7 ( https://github.com/EpicGames/UnrealEngine/commit/fb473a7678c3669bebe0431dacaf52bcf8dee47f#diff-e6f727710008f31c0ece339b76041d2e ) included in v4.23. ...

Changing the name of a native component results in a blank details panel

UE - Gameplay - Components - May 7, 2021

Much like [Link Removed] (which I'm backing down on my by design claim), there is an issue where if you previously referenced a component that no longer exists, the correct instanced subobject is lo ...

Subsurface Scattering Checkerboard with SceneColourFormat 3 (High Scalability) leads to a visual artefact when temporal upscaling is in use

UE - Graphics Features - Sep 30, 2024

Primarily visible at very low internal resolutions (25-33%), the SSS checkerboard with an RGB scene colour format (r.SceneColorFormat 3) causes a double-image artefact both internally and on the sil ...

Descriptions for vis log shapes in the Rewind Debugger are misaligned

UE - AI - Debugging - Mar 25, 2025

When recording shape information, descriptions are offset from the shape. Licensee Message - I noticed that the capsule vis log description labels were not lining up after replaying the recording ...

GAS: Double attributes not shown GameplayDebugger

UE - Gameplay - Gameplay Ability System - Aug 27, 2025

Context The Gameplay Ability System lets devs specify numerical attribute properties in UAttributeSet subclasses. Although the preferred attribute property type is FGameplayAttributeData, GAS has l ...