Hi Nicolas,
Thanks for using Syncfusion products.
Grouping a column will always sort the column. With SummaryInCaption, when you group a particular column, then the Grid is grouped and sorted based on the column. Now if you click on the other column (eg. EmployeeID) to sort, then the Grid will sort each group based on the column
(eg. EmployeeID). This is the default behavior of the control, and it works properly.
Please refer the sample from the below link, which illustrates this:
http://www.syncfusion.com/support/user/uploads/Sample_b8213fa4.zipPlease refer the video clip from the below link, illustrating the process clearly:
http://www.syncfusion.com/support/user/uploads/Summary_5309be95.zipPlease let me know if you have any other concerns.
Regards,
Raji