Key fields on the output side of a map should not be used by most customers. This feature was added to the Map Editor to provide backward compatibility for Gentran Server 2.0 users who migrated to Sterling B2B Integrator. Attempting to use output side key fields to manage map output will likely result in unexpected and unwanted processing patterns.
Diagnosing the problem
Based on the current documentation, users might understand the functionality as if the translator would just skip an iteration where the key field did not have data, and continue to process iterations after the skipped one. However, the way the translator works, as soon as it finds an empty iteration of the output repeating structure, it stops. So if it is a repeating record, or XML element, as soon as it doesn't match the key field, all further iterations are ignored. Users might also assume that any children to an XML element would not output. Instead, it's the opposite. If any child elements contain data, they will output, and in turn cause the parent to output (since you can't have children, without a parent).
Resolving the problem
Key fields on the output side of a map should not be used by most customers. This feature was added for backward compatibility for Gentran Server 2.0.