Only date gets set from pre-filled input fields, why?

Hello.
I’m working with a page that has a s form with a start and an end date.
It works good, and I have enabled time also.
I have attached calendars to two input fields. They can be set, with the calendar-ui.
But in the edit page (where the saved data is edited / opened), the time get set to 00:00, even though the date is set right.
I fill the the two fields from backend, date (and time), and then dhtmlx calendar is loaded by JavaScript.
So the time gets cleared after the dhtmlx calendar is loaded.
I want it to be set right, both date and time.
Can you help?

Please, make sure that you’ve defined the time in your date format:
docs.dhtmlx.com/api__dhtmlxform … ormat.html
Also, please, make sure that the time is saved on your server-side