A lot of information is missing when I download my submissions as PDF

Our apologies for the inconvenience.

I understand that you are viewing the submissions page, but do you see the missing data on the submissions page? If the submissions are there, then the PDF needs to be fixed manually. You may consider creating a new PDF document. 

https://www.jotform.com/help/555-Applying-Form-Submission-Data-into-a-PDF-Document

If you do not see the data on the submissions page, that means the submitters have skipped the fields since your form fields are not set as required in the form. If you require an entry on the fields, you have to consider making fields as required.

https://www.jotform.com/help/546-How-to-Set-a-Field-as-Required-or-Non-Required