Why the date picker option doesn't work in my form?

https://eu.jotform.com/build/23063810697355

Apart from the date picker that I inserted some months ago, the form works ok. It seems that when people click the picker to enter the date of their birth this data doesn't seem to stick. The whole picker seems to be ignored when all the information is assembled and then sent to the administration of the language school.  I don't know what I did wrong and hope you can help me out.

The site link: https://www.dantehaarlem.nl/bestanden/cursussen.html

I checked your form and I saw that the date field is missing from the email, but it exists in submissions.

Also, when I cloned your form the field was showing fine in my email.

Could you please try creating your notifier again and see if it resolves the problem.

Please try and let us know how it worked.

Thank you!