If I subscribe an email address that is already a civicrm contact, the system correctly joins that contact to the group.
However, that email address also receives a confirmation email for the user to click on the link to confirm the subscription (even though, since they already exist in the system with no privacy restrictions, the DO_NOT_EMAIL flag is not associated with that civicrm contact).
When the pre-existing civicrm contact follows the link from the email, the following error message appears:
invalid confirmation code, please subscribe again.
(even though the contact has already been joined to the specific group)
Does anyone else have this issue? Or any suggestions?