Hi, thanks for the patch,
I tried it but it still don’t work, i also update the contact form 7 plugin today.
I did a test removing the slider from the form and after i remove it i cand send more than one mail. After i restore the plugin, the first submission works perfectly but the second gives me validation error data. Inspecting with firebug the http response seems like the validation of captcha fails.
{"mailSent":false,"into":"#wpcf7-f4-o1","captcha":null,"message":"Si \u00e8 verificato un errore di convalida. Controlla i campi obbligatori ed invia nuovamente il messaggio.","invalids":[]}
you can check by yourself at the same link i give you before:
https://www.grein.com/staff
Hope it helps you to find a solution
thanks!