Problem date tour

Hello,
I have a problem with the various tours at the user level for the purchase, when a user tries to buy the tour he enters the data first name, last name, email, phone work, then when he has to select the date the form is not displayed to select it, furthermore if you try to add more people or children the count does not work. Why? Everything worked ten days ago. This is the example link

https://www.comeandseeitaly.com/tours/montecatini-walking-tour-from-pistoia/