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 checked your submissions and I saw that some of them have have payment details and some of them don't, because non of the products were selected. If non of the products are selected your users will not be redirected to PayPal to complete payment.
To avoid that you need to set your Paypal payment field to be required.
Hope this will help. Let us know if you need further assistance.