Whenever a user opens up the Human Connect popup, a Human API user is created for them. Tokens are only generated though when a user successfully authenticates a source--or more specifically, successfully posts to our tokens endpoint.
Users without tokens are counted as "inactive" so they do not affect totals related to pricing and can be left alone in the event the user comes back to authenticate again.
If you would like to recover a user's tokens, advise the user to authenticate their data source again in Human Connect. That will trigger the auth flow again. In the event that this is still unsuccessful, you can contact firstname.lastname@example.org to help manually generate those tokens for you.