Type of Service Does Not Change When Chosen From Dropdown List


I have set up 3 services and 3 durations:
Service #1 - 90 minutes
Service #2 - 60 minutes
Service #3 - 30 minutes

I, then, used the following shortcodes to display the appointment calendar for my services:
[app_monthly_schedule service="0"]

Here is the issue: When I go to my test page (http://www.enxaqueca.com.br/blog/pollsarchive/) and choose a service other than #1 from the dropdown menu (naturally, I also click on "Show available times), there is no change, neither in the service shown in the dropdown menu (it still displays #1), nor in the calendar's time slots (compatible with #1) or in the "check and confirm" fields when we click on an available time, where "Service Name:" is still "Service #1").

I tried to use the argument service="0" for [app_schedule_monthly], as I understood that the service would then be selected by the dropdown list. Of course I also tried the shortcode without any argument.

It seems to me that the issue is with the dropdown failing to switch from the default option.

Could you please, help?

Thank you very much!

Kind regards,