Error sending form CF7

After clicking the submit button, you receive the captcha check box. But at the same time when sending the form. I understand the form should not be sent until you shalt bring captcha. Next after entering the CAPTCHA page is reloaded and the message is sent successfully, but the letter did not come. If you disable all plug-in works well.
I recorded a video as it happens. It’s something I’m doing wrong or is this a bug?

Here is a link to the video – https://youtu.be/hkXANHPsONA?hd=1