Hey Kurt, Your confusion is justified, and we haven't done a great job of communicating what the updatedAt field actually reflects, versus what our APIs use to determine if a record has been changed within a date range. The updatedAt field only reflects changes made to the specific primary Lead/Contact table, but not all of the fields on lead records reside there, including some system managed fields, and all Custom Lead fields. The updatedAt filter for Bulk Export instead looks for Data Value Change activities within that range, and returns the associated lead records which have changes in the range. I'll make sure to update the docs to reflect this.
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