Hey @eves.iglu welcome to the forum! 
Would you be able to send over your read only link to your site? How to Enable a Webflow Share Link
Two things off the top of my head are reCAPTCHA and custom form actions.
If you have reCAPTCHA enabled and you do not have a reCAPTCHA element in your form, it will not submit.
If your form has a custom action, it will perform that action instead of using the standard Webflow Form submission.
Hope that helps! 