Copy Job: Using variable library prevents editing mappings

This looks like a limitation or bug in how Copy Job handles Variable Library references in the mapping editor.

Since the pipeline executes successfully with the variable values, but the mapping editor returns PathNotFound, it seems the runtime is resolving the variables correctly while the design-time mapping editor may not be resolving them in the same way.

As a workaround, try configuring the mappings while using hardcoded Lakehouse IDs, then switch back to the Variable Library references.

I would also suggest raising this with Microsoft Fabric support, as the mapping editor should ideally handle the same variable resolution as the pipeline execution.