Packaging issue with the source code

[RegulusHeart]

What happened?

I expected the project, which uses the Cesium for Unreal plugin compiled from source, to package and launch successfully, just as it does when using the pre-built version of the plugin in UE 5.4.

Specifically, I followed the correct workflow for integrating a source-built plugin:

1.Compile the Cesium for Unreal plugin from its source code.

2.Integrate it into a project.

3.Package the project.

I expected that the engine's packaging process ("cooking") would correctly process and include all necessary shaders for the default materials (like DefaultPostProcessMaterial), even when a complex, source-built plugin like Cesium is part of the project. The packaged game should find and use these shader maps without error.

The fact that a fundamental, engine-provided default material fails in this specific scenario (with a source-built plugin in UE 5.5) indicates a potential compatibility issue or regression in the engine's build and packaging pipeline.

Environment

Cesium for Unreal version: 2.21.0
Unreal Engine Version: 5.5.4
Operating System: Windows 11 Professional

Reproduction steps

1.Download the engine source code.

2.Compile the source code (using UE 5.5.4, MSVC 14.38.33130, Visual Studio 2022).

3.Generate a project based on the TestsProject template.

4.Package the project for Windows.

5.Launch the packaged project.

6.The fatal error occurs.
Error Message
Fatal error: [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\Materials\MaterialShared.cpp] [Line: 2966]
Failed to find shader map for default material DefaultPostProcessMaterial(/Engine/EngineMaterials/DefaultPostProcessMaterial.DefaultPostProcessMaterial)! Please make sure cooking was successful (Contains inline shaders, has GTSM)
Additional Context
The same process works without any issues in the following environment: UE 5.4.4, MSVC 14.34.31933, Visual Studio 2022.

Supporting evidence

No response

[RegulusHeart]

This fixed my error. [REMOVED LINK]

"Thanks for trying to help, but the contents of this ZIP file (msvcp140.dll and x86_64-w64-ranlib.exe) look unrelated to Unreal Engine shader compilation errors. These appear to be system/compiler toolchain files, not an actual code fix for the issue. Running random executables from the internet is also a security risk.

Could you please provide the actual Git commit or source code changes instead? This would be much safer and more helpful."

[fpibbs]

In Unreal 5.5.4 I resolved using

https://github.com/CesiumGS/cesium-unreal/releases/tag/v2.19.1

Best

[RegulusHeart]

In Unreal 5.5.4 I resolved using

https://github.com/CesiumGS/cesium-unreal/releases/tag/v2.19.1

Best

1. Status of Official Pre-built Releases:
v2.19.1: Works flawlessly. Packages and runs without any issues.
v2.21.0: Packages successfully, but contains a known LogCesium bug in CesiumGoogleMapTilesRasterOverlay.cpp.

2. Issues When Compiling from Source:
With the v2.19.1 source, the build process fails with MSVC version linking errors.
With more recent source versions (e.g., targeting v2.21.0), the build completes, but the packaged project fails to launch and throws a LowLevelFatalError related to the DefaultPostProcessMaterial shader map.

I have meticulously followed the developer-setup-windows-gotchas.md guide to ensure consistency（And have successfully built and packaged the project in UE5.4），The core issue is that the official pre-built binaries work, but my local source builds fail in different ways. This suggests a potential discrepancy in the build pipeline or environment that is not covered by the current documentation.
I would be very grateful for any guidance on resolving this.