Hi, 

We are trying to support our clients with loading existing customer profiles to Klaviyo via csv file during onboarding. After onboarding, we send customer create and update via real-time profiles API to Klaviyo. 

When sending customer data via API, we send ‘external_id’ field under the attributes section per Klaviyo documentation. 

This external_id field then gets populated correctly under ‘Profile details’ section. 

However, when I upload customer profile via csv file and input the ID under ‘external_id’ column, Klaviyo asks to map the external_id field to a new field and when it gets uploaded, it is created under ‘Custom properties’.

How can I get the external_id field to be populated under ‘Profile detail’ section when loading data via csv file?