UProceduralMeshComponent::UpdateMeshSection does not call UProceduralMeshComponent::UpdateCollision

UE - Simulation - Physics - Apr 20, 2020

Updating a procedural mesh results in an incomplete collision update. Collision bounds appear to get updated properly, but collision data is not updated, despite a navigation rebuild being triggered ...

Material Editor Viewport does not display World Position Offset

UE - Rendering - Graphics Features - Mar 19, 2026

The preview Viewport in the Material Editor does not correctly render World Position Offset. It appears that the RenderVelocities pass (which is also drawing the depth for the preview sphere) does ...

Actor Variable References settable when in type array in Level blueprint

UE - Gameplay - Blueprint - Nov 13, 2017

There is an issue with Actor Variable References that become settable when in type array in the Level blueprint. Once in the array, the actor can be successfully addressed, however using the Save Cu ...

Lighting Build Fails With High Density Foliage

UE - World Creation - Worldbuilding Tools - Foliage - Jan 16, 2018

Trying to build lighting on a map with high density foliage will fail lighting build or cause the editor to crash. This occurs in 4.15, 4.16, 4.17, and 4.18. There have been multiple reports of this ...

Can change type of event dispatcher in Blueprint

UE - Gameplay - Blueprint Editor - Oct 2, 2018

It seems that with 4.20 users are able to change a dispatcher's type from Multicast Delegate to something else (float, int, etc.) Doing so will cause any node that references the dispatcher via call ...

Child Blueprint construction script runs before parent C++ OnConstruction

UE - Gameplay - Jun 25, 2019

When the order of construction is backwards it makes it impossible to have native objects set up components in OnConstruction, that a child BP Construction Script then has access to. Sometimes the C ...

Unable to delete levels with Particles in them

UE - Gameplay - Oct 9, 2019

The engine is unable to Level that has a Blueprint actor with a child actor component that has a particle system component. The follow message pops up: World /Game/LevelName.LevelName is in use. — ...

Potential Memory Leak when frequently terminating and re-initializing FConstraintInstance

UE - Simulation - Core - Mar 29, 2022

From User: When frequently terminating and re-initializing the FConstraintInstance, there appears to be a leak when cleaning up the disabled joint, which leads to an ever growing list that gets sort ...

SetOneWayInteraction functionality has no effect on the simulation

UE - Simulation - Core - Nov 11, 2022

Calling SetOneWayInteraction on a BodyInstance has no effect within the physics engine. The state of the flag is passed in to Chaos but nothing actually uses the value once it is there. It is expe ...

[Interchange] Crash on asset re-import

UE - Editor - Content Pipeline - Import and Export - Feb 7, 2025

We've started seeing a crash in editor when re-importing one of our assets. <pre class="ql-syntax">Assertion failed: (Index >= 0) & (Index < ArrayNum) [Link Removed] [Line: 783] Array index out of ...