The hidden fields within a repeat that are calculated from a field outside of a repeat only record the first related record when more than one related record is submitted through a web browser.
This issue is not reproducible in the current version of ArcGIS Survey123. If the issue persists, contact Esri Support Services for further investigation.
解决办法
Change the field type to text, and set the hidden field as esriFieldTypeString in the bind::esri:fieldType column of the form.