When do audience insights become available?


The “reached audience” from the Twitter Ads UI is represented also in the API at https://dev.twitter.com/ads/reference/get/insights/accounts/%3Aaccount_id / https://dev.twitter.com/ads/reference/get/insights/accounts/%3Aaccount_id/available_audiences / (shown here:

What is it that determines if an audience has insights (such that it would appear in the list https://dev.twitter.com/ads/reference/get/insights/accounts/%3Aaccount_id/available_audiences / have the “View Audience Reached” link in the UI?