Before mapping loop@ merge fields, make sure that you properly set up the merge fields that are nested within your two loop@ merge fields in the RTF, as described in loop@ Merge Fields for Automatically Selecting Related or Sub-objects.
There are two steps to mapping sub-objects or related objects to be automatically retrieved:
•Mapping loop@ Merge Field to Related Object or Sub-object
•Mapping Merge Fields Nested within loop@
The Merge Field drop-down list will not display the basic merge fields that are nested in your loop@ merge fields in until you map your loop@ merge field to a sub-object or related object.