Hi Jaakko,
Thanks so much for reaching out!
I’m sorry that you have experienced this issue on your site!
One thing you can do is to alter the total_sales custom field on the WooCommerce Product page that is associated with the ticket that you are trying to edit. You can change that number to reflect the actual number of attendees that you have, which will then change what you see in your Attendees tab.
You can also alter the ticket stock on the Edit Event page, where you edit your ticket.
Let me know how it goes and if you have any other questions on this topic!
Thanks,
Jaime