Hello,
It happens because of the “work_time” option. When it is enabled, gantt doesn’t count the duration of non-working hours leading to stretching or shrinking the tasks. The problem can be solved in two ways.
Another way is to hide non-working time using “skip_off_time” option. That will change the appearance of the timeline. To make it look like in your snippet you can add an additional scale and use css to hide it: docs.dhtmlx.com/gantt/snippet/00887b8d
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