How do I fix "After adding an Iterator, downstream modules only show 'Value' instead of field names" in Make?

Question

Modules added after an Iterator were never executed in sequence before configuring, so Make has not inferred their output schema for mapping.

Accepted Answer

Run the scenario after each module addition, not only at the end: run the source, then add and run the Iterator, then add and map downstream modules. If the chain is already built, click 'Run once' on each module top-to-bottom with real data so Make registers the output structure.

After adding an Iterator, downstream modules only show 'Value' instead of field names

Cause

Fix

Hitting an automation error we have not covered?