BP Event Dispatchers: Hidden reference from actor A -> B, if B bound to A's event dispatcher editor-time, unbound later, but actor A wasn't resaved.

UE - Framework - Blueprint Editor - Feb 19, 2026

Context In blueprint, one can bind to a referenced actor’s events by clicking an actor reference variable, and creating an event node through the variable’s detail panel. Under the hood, this adds ...

Does FSlateElementBatcher::AddCachedElements need to check if r.HDR.UI.CompositeMode is enabled?

UE - Editor - UI Systems - Aug 28, 2024

When a specific configuration of HDR cvars are set, PIE in a New Editor Window will not render the game world. Settings (For DefaultEngine.ini): ```[SystemSettings] r.AllowHDR=1 r.HDR.Display.Color ...

Foliage unbuilt instances have incorrect LOD

UE - World Creation - Worldbuilding Tools - Foliage - Dec 13, 2024

From licensee: Foliage instances are not drawn correctly/the wrong LOD is selected while painting in FoliageMode. This is more apparent when setting InstanceSettings>CullDistance>Max to a value != ...

If something is blocking the One File Per Actor file, you can delete the actor inside Unreal, but the file won't be deleted and will reappear after the map is reloaded.

UE - World Creation - Worldbuilding Tools - OFPA - Nov 14, 2022

Licensee:Artist reported removed actors reappearing I suspect that file got loaded by something and tested what going to happen if you open a file for read I used python to test lock_file = R'C ...

World Partition - Deleted actors can become unloaded prior to saving

UE - World Creation - Worldbuilding Tools - World Partition - Apr 11, 2025

In world partition levels, deleted actors can become unexpectedly unloaded prior to saving, causing loss of work. Specifically, this issue occurs after the undo history has been cleared (either manu ...

Merging Splines causes Engine to Crash in 5.1

UE - World Creation - Worldbuilding Tools - Merge Actor - Dec 15, 2022

Attempting to merge two spline actors causes the Engine to crash. This issue occurs with the Steps to Reproduce regardless if there are more branches added to the tree branch spline/enabled, and reg ...

Controller Mapping/Unmapping on some platforms is not ideal for local multiplayer

UE - Gameplay - Input - Nov 19, 2025

[Link Removed] The workaround is as I posted in the UDN, to override the viewport client or to make a custom slate input mapping to change this behavior. But, there is a bug with that unmapping/l ...

[AI] WP Dynamic navmesh fails to rebuild tiles with actors that are loaded but not part of the base navmesh.

UE - AI - Navigation - Feb 18, 2025

WP dynamic navmesh does not properly react to actors or navigation modifiers that are loaded in areas that the navmesh has not yet streamed into. Although the actors/modifiers are not part of the ba ...

Crash when calling SetState inside state machine OnUpdate

UE - Anim - Sep 5, 2025

The crash happens when SetState is called inside the function bound to OutputAnimationPose’s OnUpdate in the animation state. This way of using Set State node is the same as shown in the official do ...

Chaos Trailing Events not exposed to Blueprints and only accessible via Niagara Chaos DI

UE - Simulation - Visual - Apr 22, 2025

Chaos Trailing Events not exposed to Blueprints and only accessible via Niagara Chaos DI. The licensee noticed that the Trailing event is not available to BPs. It's expected that the same data avail ...