Unreal Engine Issues
Unreal Engine Issues
Content is Missing from Cook and indeterminism: StaticMeshComponents in Blueprints that copy data into themselves from StaticMesh have indeterminism due to StaticMesh not yet finished loading, postloading, or building
UE - Foundation - Nov 12, 2025Content is Missing from Cook warnings are warnings reported at the end of cook phase of a project's data build. They report that data used by a cooked package will not be available at runtime. This ...
Large Landscapes cause long PIE start time delays
UE - LD & Modeling - Terrain - Landscape - Jan 29, 2020These delays appear with large Landscapes (for example 8029 x 8029) . The delays only start occurring after the level is saved and reopened. After which PIE start times will be 5 to 15 times longer ...
UE4Editor_SlateCore!TSharedFromThis<SWidget,0>::AsShared() sharedpointer.h:1221
Tools - Apr 18, 2017This bug report was entered as new crash groups appeared linking to [Link Removed] which was marked as fixed for 4.15.1 and the previous reproduction did not reproduce the issue Error message: Ass ...
Float Curve evaluation may yield completely wrong results due to floating-point precision issue
UE - Anim - Runtime - Oct 31, 2024Note: This is possibly related to [Link Removed]. For some inputs, function UE::Curves::WeightedEvalForTwoKeys() inside file "CurveEvaluation.cpp" can incorrectly return the value of the first key, ...
Reference to control rig can be lost on actors with multiple skeletal mesh components
UE - Anim - Rigging - Control Rig - Apr 4, 2023In the attached project, when we initially add a control rig track for the actor with multiple skeletal mesh components, we add the control rig for the correct component because FControlRigParameter ...
Changing blueprint default values inside arrays only updates loaded child blueprints
UE - CoreTech - Jul 30, 2020The 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 ...
[CrashReport] Assertion failed: TaskDataArray.Num() == Exporter->VolumetricLightmapTaskGuids.Num()
UE - Graphics Features - Lumen - Oct 2, 2017This is a trending crash coming out of the 4.18 Previews. Users have not provided any descriptions of their actions when the crash occurred, but at least two of the affected projects are being creat ...
Cannot select child anim BPs for use in linked anim layers
UE - Anim - Runtime - Jul 15, 2021From UDN: [Link Removed] Unable to set a Child ABP with inherited interface to a Linked Animation Layer Instance Class. I have a ABP_Biped which is our main ABP. I have the locomotion (idle+straf ...
Filling Vertex Colors does not propogate down to other LODs
Tools - Nov 19, 2018The original reported behavior called out that filling individual channels did not apply to LODs when LOD Model Painting = False. With changes implemented in 4627582, the initial fill will reach LOD ...
Instanced Static Meshes ignore max World Position Offset Displacement for bounds after UpdateInstanceTransform is called
UE - Graphics Features - Jun 18, 2025When an Instanced Static Mesh Component (ISMC) uses a material with a non-zero Max World Position Offset Displacement, the bounds are correctly expanded at initialization. However, after calling Upd ...