Unreal Engine Issues
Unreal Engine Issues
MovieSceneSequencePlayer GetEndTime() reports incorrect end time
UE - ACT Character - Sequencer - Jul 28, 2026We've noticed an inconsistency with UMovieSceneSequencePlayer::GetEndTime(). It does not take into account DurationSubFrames. See UMovieSceneSequencePlayer::GetDuration() for comparison. Also, the c ...
FMassMoveTargetFragment::CreateNewAction does not update PreviousAction, breaking the start-of-path avoidance fade and related behavior for MassEntity crowds
UE - Runtime - Character - Jul 28, 2026In MassEntity-based crowds, when an agent transitions from Stand to Move and begins walking, the Avoidance trait parameters StartOfPathDuration and StartOfPathAvoidanceScale, which are meant to temp ...
Issue with UHLODBuilder::ComputeHLODHash
UE - Engine Scaling - Streaming - Jul 23, 2026The HLOD content hash used to detect changes and trigger rebuilds effectively ignores everything hashed before the source-component loop — including the result of UHLODBuilderSettings::ComputeHLODHa ...
Overwriting an anim sequence may scale the play rate of the anim instead of modifying underlying frame rate
UE - ACT Character - Anim in Engine - Jul 21, 2026The frame rate for an anim sequence is not being changed as expected when its being overwritten / re-imported. ...
Can't cook a subsequent release when the project uses World Partition.
UE - Core - Data Pipeline - Cooker - Jul 14, 2026A licensee reported getting errors when cooking a subsequent release. The bug is a side effect of CL44557776 which changed the behavior when dealing with generated packages in UCookOnTheFlyServer::G ...
Crash in GC - FSharedStruct reachability race condition
UE - Core - Systems - Jul 13, 2026This Jira was created from the linked EPS case: =============================================== This issue is caused by FSharedStruct batching reachability requests to the same underlying FInstan ...
Navigation data contained entirely within a Level Instance is not registered at runtime (PIE / standalone / packaged) in a World Partition persistent level
UE - Runtime - Character - Jul 13, 2026A licensee is composing independently-authored levels into a single World Partition persistent level by placing each as a Level Instance. NavMeshBoundsVolume / NavModifierVolume are placed inside ea ...
WorldPartition RuntimeHashSet: non-deterministic URuntimePartitionPersistent UObject name causes unstable Cooked output (RuntimePartition:DebugColor)
UE - Engine Scaling - Streaming - HLOD - Jul 9, 2026During deterministic Cook / Package validation, the Cooked output of a WorldPartition map was found to vary non-deterministically between Cook runs. Diff detected in the DiffOnly Cook log:Serialize ...
Editor crashes in FAsyncLoadingThread2::ProcessLoadedPackagesFromGame when Level Blueprint references external actor
UE - Engine Scaling - Streaming - Level Instances - Jun 26, 2026Adding a reference to an external actor in the level blueprint causes the package for the actor to be put in the import table of the level. In some cases, the actor package can end up calling postlo ...
Custom expression additional outputs don't work when connected to World Position Offset
UE - Rendering - Architecture - Materials - Jun 24, 2026Custom expression additional outputs are considered (0,0,0) when connected to WPO. ...