Task is getting updated only first time- .net MVC

Hi all, I am using dhtmlxGantt for a project and it working fine. But the tasks are getting updated only first time. Can anyone help me out?

Could you clarify if the tasks are not saved to the database or they are not displayed correctly in the chart or something else?

Could you try to reproduce it with the official demo or with clean install?

Please follow these steps to help me to know where is the problem:

  1. Before updating a task second time press “F12” to open “Web console” or “Chrome Dev Tools”.
    developers.google.com/web/tools … s/console/
    developers.google.com/web/tools … /reference

  2. Now try to update the task and check the Web Console and Network tabs. Notice if there are any messages, warnings or errors.

  3. After that try enabling logging for the gantt connector according to this instruction:
    docs.dhtmlx.com/connector__php_ … idelogging
    and try to save the task again.

In case of errors or warnings, please copy all the text or make a screenshot and post it here.