Unreal Engine Issues

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

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 ...

Cook non-determinism when serializing UObject pointers pointing to garbage

There's a cook determinism issue in the way UObject unversioned serialization handles UObject pointers pointing to garbage. Depending on GC timing, it can either be skipped (as a property matching C ...

"Detaching from existing linker" error messages when running Fixup Redirectors commandlet

Heterogeneous Volume Actor causes ensures to trigger in Debug builds

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 ...

Slow editor/PIE loading of UWorldPartitionHLODSourceActorsFromCell

Loading UWorldPartitionHLODSourceActorsFromCell takes a lot of time in editor + PIE when it contains a lot of actors per UWorldPartitionHLODSourceActorsFromCell (between 2K and 2K actors). ...

Slate text layout AllowPerCharacterWrapping issue

Customer-reported bug in TextLayout (AllowPerCharacterWrapping): Issue seems tied to bHasTrailingText handling in TextLayout.cpp (~line 694). The remainder handling after wrap inserts an extra break ...

Missing PSO Precaches in the engine

A licensee wanted to report some missing PSO Precaching they found, which they have fixed locally: 1. UCableComponent doesn't implement CollectPSOPrecacheData or call CheckPSOPrecachingAndBoostPri ...

Sub-world partitions do not properly handle partial editor loading as world partition standalone level instances' spatially loaded actors do not get loaded even when the Level Instance is force loaded or loaded in by region.

Context Level Instancing is a level-based workflow designed to improve and streamline the level editing experience. In a standalone Level Behavior, when the Level Instance Actor is loaded through it ...

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

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 ...

ULevelInstanceSubsystem::CreateLevelInstanceFrom() is not honoring parameters bAlwaysShowDialog and LevelPackageName

A Level Instance or Packed Level Actor can be created through editor scripting by using function ULevelInstanceSubsystem::CreateLevelInstanceFrom(), which receives parameters packed in the FNewLevel ...