Hi Van,
Thank you for your interest in Syncfusion products.
We are not able to reproduce the mentioned issue. Could you please find the sample from the below link. Please try running the sample and let us know if this helps.
Sample:
http://files.syncfusion.com/support/DocIO.Web/Forum/90991/CellPadding.zipPlease let us know if you have any questions.
Regards,
Jafrin J