Good evening Paula and welcome back!
Thank you for reaching out to us.
You are right, the attendee data editor plugin broke as a result of the complete Event Tickets and Event Tickets Plus redesign. We apologize for the inconvenience caused by this glitch.
We are actively working on a solution for this.
The good news is that we are working on a fix for this.
Alas, I cannot guarantee when it will be fixed, as it’s in the development team’s hands now.
They need to assign it, code it, test it, and schedule it for release.
But you will be contacted as soon as a fix is available.
Thank you for your patience as we see this through.
In the meantime, the only option is to downgrade both Event Tickets (4.5.7) and Event Tickets Plus (4.5.6) to a previous version
Aafter a backup of your database, I recommend reading the following: https://theeventscalendar.com/knowledgebase/downgrading-plugin-past-version/
Best regards,
Geoff B.