Hi Laura!
Thanks for getting in touch with us! I’d be happy to help you with this topic.
First, please make sure you are using the latest versions of our plugins. Remember you can always download our plugins from your downloads page > https://theeventscalendar.com/my-account/downloads/
my existing tickets are not showing under my woocommerce product list
If those tickets were previously created using Tribe Commerce, they will not show up as a product in WooCommerce. If you have multiple commerce platforms enabled to sell tickets, you will need to select one from the tickets settings when editing an event. In the following screenshot you can see where to select that:

Even though you can create WooCommerce and Tribe Commerce tickets for the same event by switching from one another, this is not recommended.
Additionally, let me share with you the following article that explains in further details the tickets creation process > https://theeventscalendar.com/knowledgebase/making-tickets/
I hope that helps. Let me know if any follow up questions 🙂
Best,
Victor