Iris - actors spawned/loaded before a connection exists will not use delta compression

UE - Networking - Iris - Sep 24, 2025

FDeltaCompressionBaselineManager::CreateBaseline will return early if the object has an invalid ObjectInfoIndex, which is allocated in FDeltaCompressionBaselineManager::UpdateScope (by calling FDelt ...

Ensure when calling server RPC from BeginPlay for a component that is not replicated by default

UE - Networking - Sep 18, 2025

This seems to occur due to the order in which the component is registered and set to replicate in UActorComponent::OnCreatedFromReplication. The component is first registered with the world, which c ...

Mover character stuck continuously correcting movement after having a skeletal mesh as movement base

UE - Gameplay - Player Movement - Mover - Sep 8, 2025

Once a mover character has had a skeletal mesh set as its movement base, it appears to get stuck in a desynced state after moving to a static movement base. It is only when the character's movement ...

Invalid GUIDs on new material instance parameters cause overrides to break on base param rename

UE - Rendering - Architecture - Materials - Sep 3, 2025

When a parameter value is assigned on a newly created material instance (constant or dynamic) using Set***ParameterValueInternal, the parameter’s ExpressionGUID is left invalid (0,0,0,0). Parameter ...

Negatively scaled box collisions render back faces in Player Collision debug view

UE - Runtime - Deformable - Sep 1, 2025

The player collision debug visualization for negatively scaled boxes is rendering the back faces, not the front faces. The debug primitives are rendered via the dynamic mesh builder. FDynamicMeshBui ...

UMG Retainer Box renders incorrect colors with Color Vision Deficiency enabled

UE - Editor - UI Systems - UMG - Aug 27, 2025

When using a Retainer Box in UMG with Color Vision Deficiency enabled, the content inside the Retainer Box is rendered with incorrect colors compared to the rest of the UI. This bug is present in UE ...

Heterogeneous Volume Actor causes ensures to trigger in Debug builds

UE - Niagara - Aug 24, 2025

When a heterogeneous volume actor is used with a volume material in a debug build, the following ensures are triggered: Ensure condition failed: UniformBufferValue || EnumHasAnyFlags(AutomaticallyBo ...

Copying a grouped MaterialInstanceParameterDetail property that has spaces on it's name does not enclose it in double quotes, and later pasting won't work as expected

UE - Rendering - Architecture - Materials - Aug 24, 2025

Copying a grouped MaterialInstanceParameterDetail property that has spaces on it's name does not enclose it in double quotes, and later pasting won't work as expected. The licensee noticed this in a ...

Niagara Data Interface "Errors and Warning" section on Module Details not updating when error messages change

UE - Niagara - Aug 14, 2025

This is a regression: it worked correctly up to UE 5.5, but not in 5.6 or mainline latest. Possibly caused by CL 40093049. Class UNiagaraDataInterface provides virtual method GetFeedback(), which a ...