This record is only created through the update matrix function on the item record.
Hello @denisejames
The UserEvent script which is responsible to create these Item ID map records, do not trigger when there are updates to Item records using any CSV import.
Can you please confirm if you are trying to sync the Item ID maps for the Items existing in BigCommerce store, or are these new items which you require to export to BigCommerce If those items are already in BigCommerce store, you make use of the Mass Item ID import flow which we provide within the IA. Actually this is a Add or Update flow. So, if there is no existing item id map linked to the item record, the flow will create a new Item ID map and attach it to the item. And from the next run, it will update the existing Item ID map.
Please let us know for any further queries.