Unable to select date part

[pastoolio]

I have a date / time field with a format similar to this:

2018-06-26 15:27:00

The seconds will always be 00. My issue is when I want to edit the date part I can't select a new date from the popup calendar, but the time can be selected and updates the field accordingly.

Here is my code:
$('#frm_add_lead_email_reminder #sendon').datetimepicker({ dateFormat: "yy-mm-dd", timeFormat: "HH:mm:00", showAnim: "slide", stepMinute: 15 });

There are no errors or warnings being logged so I am not sure what I am doing wrong.
Can someone please point me in the right direction?

Thanks a mil!

[pastoolio]

I have now completely trimmed the 00 seconds part but I still can't select the date from the widget. The time sliders do update the time part but clicking on any date does nothing.