Hi there,
Thanks for reaching out. I will try to help with your issue.
The setting that allows you to add an image in the tickets interface is for the image that gets included with the ticket email only. Unfortunately, there is not a way to have an image assigned to a specific ticket.
Your other option would be to use the event featured image, but this is also for the whole event, and not a specific ticket.
Hope that helps! Please let me know if you have additional questions about this.
Thanks,
Sky