Contact Form Does Not Close When Clicking Submit

I just purchased the PRO version and this is a serious problem.

When a user completes a form and clicks the submit button, the form stays open for about 18-25-seconds. The form does not close, so it appears to the user that the form was not sent.

If one waits long enough (about 18-25 seconds) after clicking submit, the green thank you message text does finally appear below the form. The same thing happens if you set up the thank you message to redirect to another page.

The expected operation would be for the form to close immediately after the submit button is clicked. Or there should at least be some kind of indicator that lets the user know the message is in the process of being submitted.

This issue makes this plugin unusable!

Can you let me know when this will be fixed? If not, I will need to request a refund of my PRO subscription.