Appointments+ is not displaying the confirmation form when clicking on the available time

Appointments+ is not working fine on my site. I can see the calendar and the available times are properly displayed when clicking on a date, but after clicking on the time slot nothing happens, the confirmation form is not displayed and I can’t book any appointment.

I tried running a plugin/theme conflict test and I also tried deactivating all the add-ons that I had active on the plugin but the issue is still there.