Today we released version 6.00.24. This version has a few bug fixes that have been creating problems on the registration form with certain themes and plugins. Additionally there were a few coding errors as well.
One fix that occured in version 6.00.20 that created an issue was in the confirmation mails not showing all the tags as noted. This has been addressed.
It is strongly recommended to deactivate and reactivate the plugin at least once after it is upgraded and activated for the first time.