Hello,
When you disable the round_dnd_dates parameter, Gantt won’t round the task to the nearest scale border. The task will have the same position where you placed it. So, it is expected behavior that the tasks don’t always start at the beginning of the day.
You need to manually round their dates with the gantt.date.day_start method in the onAfterTaskDrag event handler: https://docs.dhtmlx.com/gantt/api__gantt_date_other.html https://docs.dhtmlx.com/gantt/api__gantt_onaftertaskdrag_event.html