What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
I did a test submission on your direct form and I didn't encounter any issues with it. After hitting the submit button, it redirected me to the Thank You page.
If this form is embedded on a webpage, please try re-embedding the it using the Iframe method. Here's a guide: https://www.jotform.com/help/148-Getting-the-form-iFrame-code
If the issue is still the same, let us know. Please provide that webpage URL where the form is embedded. Thank you.