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.
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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.
Sorry for your inconvenience.
I tested your form in both standalone version and in your website but I cannot replicate the same error. After I submitted a test in your form I checked your submission page. Here is the screen shot.
I also noticed the empty cell in your spreadsheet but I checked the fields in your forms, the fields are not required so your user can leave it empty if they want. So I suggest that require all the important fields in your forms.