Unreal Engine Issues

Values for InitialOnly replicated arrays can fail to be captured in replay when removed and re-added between checkpoints

When the first checkpoint is recorded, the correct array properties will be captured in the LifetimeChangelist. When these array items are later removed and another property on the actor is changed, ...

Failed to generate Nanite data for mesh with bDoFastBuild enabled

If "bDoFastBuild" is enabled on a Static Mesh asset, in-editor it will never be able to have Nanite data built for it, preventing the Static Mesh from using Nanite. There is no way to fix this issu ...

Pathtracer - Odd results from any material adjusting normals to complement world position changes

Someone on the forums is reporting a possible bug with Pathtracer and any material that adjusts normals to complement world position changes. See pic attached. Reporting forum thread:https://foru ...

Merge Actors (Simplify) is broken with Substrate Shader Models Node

Substrate Materials cannot be baked when Meshes are merged using the "Simplify" method. All textures except for the normal are reduced to a single black parameter. The normal texture produced does n ...

nDisplay Regression: Public header DisplayClusterViewport_OverscanSettings.h now includes internal header Math/MarginSet.h, breaking clients' code

On the nDisplay plugin code, CL 44773085 from August 12 introduced a new struct template TMarginSet and changed struct FDisplayClusterViewport_OverscanSettings to use it. However, the latter is defi ...

DeltaCompressionBaselineManager needs to update its scope for minimal update

DeltaCompressionBaselineManager needs to update its scope for the case where objects may be replicated but no connections exist. ...

Virtual texture fallback displays in incorrect color space on mobile platform (VT:OFF) Preview

Custom Depth range is different than Pixel Depth range

Shaders that compare custom depth and pixel depth get wrong output values because the ranges are different. This error is most noticeable over large distances. The difference in ranges is due to t ...

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

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

Xcode 26/16.4 Metal Toolchain generates metallib's that are not compatible with iOS 16

Below is the error output from FirstPerson template as a C++ project: {+}../../../FirstPerson58CPP/Content/firstperson58cpp_sf_metal_es3_1_ios-metal_es3_1_ios.0.metallib, 5881486 bytes!2025-09-23 1 ...