Unreal Engine Issues
Unreal Engine Issues
Niagara Regression - Looping particle with Spawn Burst Instantaneous on time 0.0 flickers for a frame between loops
UE - Rendering - Architecture - Niagara - Jul 16, 2025Note: This worked correctly up to UE 5.4, but repros from UE 5.5 up to mainline latest. If a Niagara Emitter is set up with "Spawn Burst Instantaneous" on time 0.0, and the spawned particle(s) have ...
GPU event descriptions are not properly formatted in Insight
UE - Rendering - RHI - Jun 24, 2025Context Unreal Insights displays Timing Insights that can include GPU timing information. Rendering code such as FDeferredShadingSceneRenderer::RenderPrePass() generate such events.Problem Certain f ...
Change uses of "OnlineSubsystemSteam" module name
UE - Online - Jun 19, 2025The refactor at CL 39638561 moved some classes, such as SteamNetDriver and SteamNetConnection, from the "OnlineSubsystemSteam" module to the new "SocketSubsystemSteamIP" module. There are still a f ...
Significant hitch occurs when invoking ApplySettings on a UGameUserSettings object
UE - Rendering - Features - Jun 18, 2025Calling the ApplySettings method on a UGameUserSettings object results in a noticeable hitch, with severity proportional to the number of primitive components present in the scene. This hitch stems ...
New material translator: Switch statement not derivative aware
UE - Rendering - Features - Jun 13, 2025Analytical Derivatives are not calculated properly when using UMaterialExpressionSwitch. Disjoint UVs in screen space result in large jumps in the derivatives, which can cause artifacts as the wrong ...
In editor, sub level instance's streaming state persists incorrectly after toggling Level Behavior without saving
UE - Engine Scaling - Streaming - Level Instances - Jun 11, 2025When adding a sub level with world partition streaming to a main level where the streaming is also enabled, setting* Level Behavior* of the sub level to Standalone, and saving the result, in the fir ...
Copying a Folder that contains the space character from the Outliner does not enclose the Folder name on Double Quotes. Because of that, later Pasting will only handle the first word of the Folder name.
UE - Engine Scaling - Streaming - Jun 10, 2025Copying a Folder that contains the space character from the Outliner does not enclose the Folder name on Double Quotes. Because of that, later Pasting will only handle the first word of the Folder n ...
Dynamically Spawned Level Instance Actors do not have their sub actors world partition stream in PIE starting level
UE - Engine Scaling - Streaming - Level Instances - Jun 10, 2025We are building levels where we spawn in Level Instance actors at runtime that have World Partition enabled into a Persistent level that also has World Partition enabled. What we have noticed though ...
Editor vs Runtime: Inconsistent data layer behavior when attaching actors
UE - Engine Scaling - Streaming - 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. ...
Collision Drawing in Cooked Builds (Development) doesn't Show Geometry for Nanite Meshes
UE - Rendering - Features - Jun 2, 2025Context The showFlag.CollisionVisibility 1 cvar is a viewport visualization mode that highlights which Actors will block visibility. The showFlag.CollisionPawn 1 cvar is a Player Collision viewmode ...