After the latest Segment UI update, I encountered an error where custom attributes cannot be added to new profile data when sending it from Segment to Klaviyo. Specifically, there’s no option to map the field when the “upsert profile” setting is selected for Klaviyo as a destination. This issue does not affect existing events, which continue to work fine.

this is only happening in case an upsert profile is selected in Klaviyo as a destination