Unreal Engine Issues
Unreal Engine Issues
Editor vs Runtime: Inconsistent data layer behavior when attaching actors
UE - World Creation - Worldbuilding Tools - World Partition - Jun 5, 2025In editor, data layer system respects the data layer settings for each actor, but at runtime, the condition check is made collectively for each actor cluster, resulting in differences in behavior. ...
Stale VSM pages after HLOD transition
UE - Graphics Features - Shadows - May 23, 2024Virtual Shadow Maps do not invalidate pages when HLODs replace meshes. This can lead to inconsistencies between the geometry and the shadows, which can cause artifacts as pages are invalidated. ...
Placed level instance causes "!ActorInstanceGuid.IsValid()" assertion after changing WorldSettingsClass
UE - World Creation - Worldbuilding Tools - Level Instances - Nov 13, 2023Resaving the level using ResavePackagesCommandlet is a workaround. ...
World Position is incorrect when used to control the opacity mask in a nanite spline mesh
UE - Graphics Features - Feb 20, 2025When calculating the opacity mask, Nanite spline meshes do not have the correct World Position in the Material. This leads to visual artifacts when the mask relies on the world position. ...
Masked material using virtual textures covering a decal will result in black pixels
UE - Graphics Features - Nanite - Mar 31, 2025Depth Passes for Masked Materials using Virtual Textures does not work correctly when it is in front of a Nanite Mesh and a Decal, resulting in black artifacts. Also tested on //UE5/Main, CL: 41024 ...
World position offset (WPO) and nanite enabled causes shadow of complex static mesh actor to be deformed at a specific distance
UE - Graphics Features - Nanite - Dec 19, 2024Context / Problem: Complex static mesh actors with nanite enabled and Evaluate World Position Offset (WPO) enabled works together except for a specific distance where the shadow is deformed and sort ...
Masked TwoSided material causing lumen direct lighting to leak through walls
UE - Graphics Features - Lumen - Apr 23, 2024It appears that LumenScene's Hardware Ray Tracing is causing light leaking into a sealed room (which should be perfectly black). This bug does not appear to happen on AMD GPUs. ...
High Virtual Texture Sample/Lookup Cost when using a Virtual Texture in a Material Layer Blend
UE - Rendering Architecture - Materials - Mar 14, 2025Some Material Attribute blends in Material Layer Blends can cause Virtual Texture samples to be duplicated in HLSL. This can be avoided by sampling the Virtual Texture in the Parent Material, and pa ...
Packed level actors and Level instances are sometimes not included in HLOD build on a World Partition Level
UE - World Creation - Worldbuilding Tools - HLOD - Mar 14, 2025Context World Partition - Hierarchical Level of Detail (HLOD) system uses custom HLOD Layers to organize large amounts of Static Mesh Actors and generate a single proxy mesh and Material. Problem T ...
Water tiles flicker in and out of visibility with instanced stereo enabled.
UE - Graphics Features - Jun 16, 2025Water tiles flicker in and out of visibility when playing in VR with instanced stereo enabled. Requires instanced stereo rendering to be enabled (does not require forward shading to be enabled) Must ...