I am running WooCommerce as my ecommerce gateway and same issue occurs. I can access attendee data when I click through on the attendees link from the event page but the Attendees values are showing as 0 on the Events list page (edit.php?post_type=tribe_events). I have tested for conflicts and there is no problems with theme and plugins.
This seems to be an ongoing issue with this plugin and is becoming very frustrating so hopefully this time the dev team will find a permanent fix for it.
PLEASE LEAVE FOR SUPPORT
Reporting the same issue as: https://theeventscalendar.com/support/forums/topic/all-successful-orders-not-showing-up-in-attendees-list-part-2/