Unreal Engine Issues
Unreal Engine Issues
Sequencer.AllowPausedClock makes Audio/Platform-clock sequences evaluate at a negative time after any earlier game pause
UE - ACT Character - Sequencer - Oct 17, 20265.8 added Sequencer.AllowPausedClock (on by default) in FMovieSceneTimeController_ExternalClock::OnRequestCurrentTime (MovieSceneTimeController.cpp): PausedTime = Context.World()>RealTimeSeconds - ...
Open Formats: FBX Reimport - interchange reimport bug 5.7 -> 5.8
UE - VEI - Open File Formats - Oct 16, 2026This is a related bug to this interchange fbx one [Link Removed] that is also triggered by reimporting a 5.7 mesh in 5.8 It looks like the asset import data has a property called `node_unique_id` ...
Open Formats: USD Reimport - settings for USD not getting stored
UE - VEI - Open File Formats - Oct 16, 2026Legacy USD importer doesn't remember import options after editor restart. Issue affects both 5.7 and 5.8. The user's choice for "Kinds to Collapse" is stored as a editor preference rather than per a ...
Open Formats: FBX Reimport - Reimport settings for FBX not getting stored
UE - VEI - Open File Formats - Oct 16, 2026FBX assets originally imported in 5.7 lose their "Combine Static Meshes" import setting when reimported in 5.8. In 5.8 "Combine Static Meshes" was changed from a bool to 3-way enum, and the old bool ...
Nanite Voxel material with Static Lighting fails shader compile when r.VelocityOutputPass=1
UE - Rendering - Features - Nanite - Oct 16, 2026Engine/Shaders/Private/Nanite/NaniteVertexFactory.ush:959LightMapCoordinateInput = GetTexCoord(Cluster, uint3(Verts[0].VertIndex, Verts[1].VertIndex, Verts[2].VertIndex), Barycentrics, LightMapUVInd ...
SceneCulling: MarkCellBoundsDirty overwrites dirty flags, leaving static chunk explicit bounds stale when a cell gets static and dynamic marks in the same frame
UE - Rendering - Architecture - Oct 14, 2026Summary FSceneCullingMarkCellBoundsDirty(CellIndex, bStaticChanged, bDynamicChanged) (Engine/Source/Runtime/Renderer/Private/SceneCulling/SceneCulling.cpp, ~line 1907) assigns DirtyCellBoundsMaskStat ...
GeometryCache: data race between FGeometryCacheSceneProxy::CreateHitProxies and the render-thread FrameUpdate enqueued by the proxy constructor
UE - Rendering - Architecture - Oct 13, 2026Symptom An intermittent ensureMsgf fires in the editor when a level contains a UGeometryCacheComponent: Array has changed during ranged-for iteration! (TArray ranged-for iterator check, Array.h). T ...
Sequencer: Entity task Pre/Post callbacks are skipped despite ForcePrePostTask when a required component is absent
UE - ACT Character - Sequencer - Oct 13, 2026Tasks scheduled through the entity task builder with FTaskParams::ForcePrePostTask() are documented to run their PreTask and PostTask callbacks even when there is no work for the task body. This gua ...
[Landscape] weightmap layer allocations leak into left/top/top-left neighbor components
UE - Graphics Tools - Terrain - Landscape - Oct 13, 2026In 5.8, weightmap layer allocations of a landscape component leak into its left, top and top-left neighbor components when Edit Layers are merged. Neighbors end up with layers that were never painte ...
Deadlock in URigHierarchy
UE - ACT Character - Control Rig - Oct 12, 2026We are regularly hitting a deadlock on 5.8.3. We have one background worker evaluating an animation, holding the RigHierarchy's ElementsLock and waiting for the global GC lock And one Background w ...