Add Submix Effect Blueprint Does Not Have Any Effect

UE - Audio - Dec 11, 2020

Adding a second effect to the Submix Effect Chain on a Submix works as expected, but when trying to add a Submix Effect via Blueprint, there is no effect.  This also applies to "Add Master Submix Ef ...

[CrashReport] Mac crash - TArray<FDeferredMacEvent, FDefaultAllocator>::ResizeGrow

UE - Platform - Apple - Sep 14, 2017

This is a somewhat common crash on Mac that has affected users since 4.16. Users have not provided any descriptions of their actions when the crash occurred. Callstack from Log [2017.09.08-05.17. ...

Get Mouse Position Blueprint node returns different values outside of viewport depending on whether it was called from Event Tick, or within an Actor function

UE - Gameplay - Nov 15, 2018

There seems to be a discrepancy between the output of Get Mouse Position node depending on whether the node is inside an Actor function or called from Event Tick. If the node is present inside a fun ...

Crash when casting to owner from AnimGraph

OLD - Anim - Sep 6, 2016

Crash occurs when casting back to the pawn owner from the Anim Graph. In this case, it is being used for "Copy Pose from Mesh" Workaround: Cast to Owner from Event Graph, defining variable as the ...

[CrashReport] Crash on Mac related to editor close

UE - Platform - Apple - Jun 6, 2017

This is a long-standing Mac crash that occurs with low frequency, but has affected more than 500 users since it started (possibly in the 4.11 release) It has recently been experienced internally by ...

Changing blueprint default values inside arrays only updates loaded child blueprints

UE - CoreTech - Jul 30, 2020

The rules for delta serialization in UE4 are complicated, and the editor tries to hide them from you, which works 90% of the time but can lead to confusion and data loss in other situations. In the ...

Niagara Scalability Crash When Processing Significance

UE - Niagara - Jun 4, 2025

Method FNiagaraScalabilityManager::ProcessSignificance() iterates on indices from Context.SignificanceIndices and uses them to access the State and ManagedComponents arrays. It can then decide to cr ...

POST /v1/testdata API doesn't properly convert data to BSON

UE - Foundation - Horde - Server - Jun 24, 2025

Post: { "jobId": "685b12ad6765a5c9fefad260", "stepId": "a991", "key": "output-otem-job2", "data": { "Type": "Simple Report", "TestName": "EditorClientBoot", "Descript ...

Race condition in full builds of UE4 engine source

UE - Foundation - Cpp Tools - UnrealBuildTool - Sep 26, 2019

This is a race condition caused by how "Clean.bat", a batch file used during rebuilds, tries to manually rebuild the UnrealBuildTool project when it runs. This causes a spam of UnrealBuildTool build ...

Culling Distances Not Working For Static Mesh in Procedural Content Generation Tool and Foliage Tool

UE - World Creation - Procedural Tools - Mar 28, 2025

When creating Foliage or Procedurally Generated Content the culling settings of the Static Meshes do not apply correctly. As soon as either a minimum or maximum cull distance is set the Static Meshe ...