Unreal Engine Issues
Unreal Engine Issues
Saving Behavior Tree with Blueprint task inheriting from native class invalidates Blackboard key when BP contains a function
UE - AI - Jul 8, 2025A regression introduced in UE 5.6 causes Blackboard key selectors in Blueprint tasks to become invalid when the Blueprint inherits from a native subclass of UBTTask_MoveTo (or UBTTask_BlackboardBase ...
Crashes after destroying a skeletal mesh attached via socket name (not bone name), the destroyed mesh remains welded.
UE - Simulation - Core - Jul 18, 2025On welding physics bodies during primitive component attachment, UPrimitiveComponent::WeldToImplementation() calls GetRootWelded() and then GetBodyInstance() on the returned root. This searches by b ...
Geometry Collection cluster handles leaking and causing ensures with field systems
UE - Simulation - Visual - Aug 26, 2025Geometry Collection cluster handles leaking and causing ensures with field systems. The licensee has shared their analysis: We have been tracking down an assert that seems to happen occasionally wh ...
Copy-pasting an actor property that is a set of strings adds extra quotes and escapes
UE - Editor - Workflow Systems - Aug 24, 2025Copy-pasting an actor property that is a set of strings adds extra quotes and escapes. The licensee has reported: The problem doesn't happen for example for properties of types set of integers, nor ...
BoxOverlapActors fails to catch an Overlaped actor with a particular scale, from a particular position
UE - Simulation - Core - Sep 30, 2025BoxOverlapActors fails to overlap a scaled Floor actor with a particular scale, from a particular position and extent. The setup is really specific and described in Steps to Reproduce. The required ...
Ensure triggered in FBoundsCacheElement::GetValue when adding ISM instances in Construction Script
UE - AI - Oct 8, 2025An ensure is triggered in FBoundsCacheElement::GetValue when adding instances to an InstancedStaticMeshComponent inside a Blueprint’s Construction Script. This occurs when the ISM component is navig ...
Rotated RetainerWidget does not account for rotation during hit testing
UE - Editor - UI Systems - Jan 21, 2026Hit testing for widgets contained within a RetainerWidget does not correctly account for rotation applied via render transforms . While the content renders with the expected rotation, hover and clic ...
FBX Export - StaticMesh export to FBX crashes if UVElements has more channels than VertexInstanceUVs
UE - Editor - Content Pipeline - FBX - Jan 22, 2026As indicated in the repro steps, we have a StaticMesh asset that, for some reason, has a mismatch in their serialized bulk data where:MeshDescription->GetNumUVElementChannels() == 2FStaticMeshConstA ...
Cloth - Assertion failed: SimData->LODIndex != INDEX_NONE && SimData->LODIndex <= LOD when using the rewind debugger with multiple LODs cloth
UE - Simulation - Visual - Feb 19, 2026The LOD switching when the simulation is paused could still be causing problems when the simulation is paused while the LOD indexes are going up because there is no LOD Bias mappings by default. Se ...
Virtual texture thumbnails appears brighter (incorrect sRGB/gamma) in content browser after asset is loaded
UE - Editor - Dec 9, 2025This is a regression, it worked correctly up to UE 5.5 but behaves incorrectly in UE 5.6 up to latest. When a regular texture with sRGB enabled is converted to a virtual texture, its thumbnail in t ...