Hi Khanh dang,
Thanks for contacting Syncfusion support.
We have prepared a sample using DataTable to replicate the reported scenario. Unfortunately we are unable to reproduce the reported issue in column generation. The sample we have used to check this issue is available in the following link for your reference.
Please have a look at this sample. If still the issue exists, please let us know if we have missed any customizations you have done in your application or try to reproduce the issue in the above given sample. It will be helpful for us to find the exact cause for the issue and to provide a prompt solution at earlier.
Regards,
Mohanram A.