So I was sitting here doing everybody's recommendation. I'm getting the same issue. User would put information presses send, the spinning icon keeps spinning but message is actually sent successfully. No errors via firebug either.
I have tried almost every ideas.
- Downgrading to an older version of CF7
- Disabled all plugins. Even deleted myPHP Database
- Took of any Analytic codes, any cache plugins.
This seemed to have WORKED~!
So I tried what @Fabian was doing, and started to edit "contact-form-7\includes\js\scripts.js"
As I decided to backup the original file renaming it to "scripts_old.js and dragging it to my desktop (using FileZilla FTP) Anyways I started to mod the original file via Dreamweaver. I tried refreshing my Page with the form, not realizing I don't have the "scripts.js" file on the actual server its still on my desktop. The form submitted successfully! So I tried several test runs and it all worked. The only difference is that The animation of the box with green border that says your submission is successful doesn't animate. Instead it seems the page refreshes.
So my fix delete/backup scripts.js see if that helps!