Is there a solution if the calendar is not displayed? When I change the theme to twentytwenty everything works fine. Switching back to my theme makes troubles. I can see the form fields but not the calendar. When inspecting the source code i see that there is one difference at the tag which normally contains the calendar: <div class="date"></div> In a working calender there I see <div class="date hasdatepicker" id="anynumber">  What's wrong with it? How could this depend on the theme? Are there any additional frameworks needed (jquery is loaded)