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 have cloned your form and I wasn't able to replicate the problem. I visited your form (https://www.jotform.com/60362122921344) and did a test submission. I was able to submit the form and after that, the thank you page shows up.
Based on the screenshot, it seems that you trying to submit the form while you are in the Preview mode. Can you please open the actual form and try using that for a test submission?
Let us know if the issue persists. Thank you.