Hey Andrew,
Thank you for picking up the Eventbrite Tickets plugin! I’d be happy to help investigate. First, you’ll need to make sure the event status on Eventbrite is ‘Public page‘. The ticket box will not display if the event status is set to ‘Private page‘ on Eventbrite.com. (see screenshot below)
You’ll also need to ensure the ‘Display tickets on event page?‘ option is set to ‘Yes‘ on the add/edit event page. (see screenshot below)
Please let me know if my response helps and if you’re still experiencing troubles, be sure to review the Testing for conflicts guide to make sure there is not a theme and/or plugin conflict in play.
Thanks again and have a great weekend. Cheers!