When you map a Loop in Repeating Section where the Repeating Section is also mapped, the syntax will need to be different to when you are mapping from the Object record running the Smart Form. 



Example 


Repeating Section Mapping Tab 



Loop Within Repeating Section Mapping 



  • Field Mapping: This should be RelatedListRecords:RepeatingSectionRelatedRecord . In the example above, the Section is set to iterate through Work Order Line Item records, so the Loop's parent Lookup Object is a single Work Order Line Item Object record. 
  • Relationship Field name: API Name of the Salesforce Field that connects the Related List to its parent (Lookup or Master-Detail). In the example above, WorkOrderLineItemId is the API Name of the Salesforce Field that connects Product Request records to a Work Order Line Item record.