Hey, @RevAnalytics 
To echo what support said, `“hs_analytics_source_data_1”` Original Source Drill-Down 1, is a read-only property. This property cannot be manually set in-app or via the API. “Please note: the drill-down properties are automatically set by HubSpot and cannot be updated manually.” — Source Unfortunately, there is not a way to “force” the API to accept values for a read-only property.
Please let me know if you have any additional questions! — Jaycee