Primary Asset Manager assets failing to cook in production builds

Resolution

To force the Unreal Engine cooker to include assets managed by the Primary Asset Manager that lack hard references, you must explicitly define their directories in the project packaging settings. The Asset Manager handles runtime loading and bundling, but it does not inherently signal the cooker to include assets that are only referenced via soft paths.

Required Configuration

While most configurations are handled via the Project Settings UI, the following key in DefaultEngine.ini ensures the cooker scans the specific directories containing your Primary Assets:

[/Script/UnrealEd.ProjectPackagingSettings]
+AdditionalAssetDirectoriesToCook=(Directory="/Game/Path/To/Your/Assets")

Likely Cause: Static Analysis vs. Dynamic Loading

The discrepancy occurs because the Unreal Editor loads assets dynamically from the local disk, whereas the production cooker performs a static dependency crawl. If your assets are only referenced by TSoftObjectPtr or strings, the cooker sees no "hard" link from a cooked map or game instance to those assets. Consequently, they are stripped to optimize build size.

Verification Steps

To determine if assets are being skipped due to bundle resolution or missing references, use these methods:

• Analyze Cooker Logs: Search the packaging output log for LogPakFile or LogCook warnings. Look for entries stating an asset was skipped because it was not referenced.
• Inspect Asset Flags: Right-click the asset in the Content Browser and verify that neither the Editor Only nor Never Cook flags are enabled.
• Pak File Audit: Use the Unreal UnrealPak.exe tool to list the contents of your generated .pak files. If the asset path is missing entirely, the issue is a cooking failure; if the path exists but the asset fails to load, the issue is likely bundle resolution or a runtime path mismatch.

Diagnostic Requirement

Are you using "Cook only maps referenced in the game" in your Packaging settings? If this is enabled, the AdditionalAssetDirectoriesToCook list is the only way to include non-referenced Primary Assets without adding them to a map.