I have added a new Campaign to your site, but it does not ask me to choose the 3rd party to connect software and list into it. But it should be asked to choose the available 3rd party to connect software like MailChimp, GetResponse and then the list where you need to add the specific form responses. In your case, it never asked and added the Campaign directly.
There might be some different reasons behind your reason, I would like to suggest troubleshoot the following common issue to help us to recognize the reason.
2.Theme Update related issue
3.Child Theme Related issue
If you discover that an issue is coming from a custom code or 3rd party plugin, kindly consult with a developer or contact the plugin author. Please note that we do not provide support for custom codes and 3rd party plugins.
If none of the above helps, please copy your live site to a staging server so we could troubleshoot freely without breaking your live site.
And give us access in the secure note including:
– WordPress Site URL & Login URL
– WordPress Admin username/password
To create a secure note, click the key icon underneath any of your posts.