Hi Sam,
Thanks for using Syncfusion products.
We are sorry for the delay.
We suggest you to set the DataSourceCachingMode as ViewState
to avoid the issue. Please refer the below code snippets.
[Default.aspx]
<Syncfusion:GridGroupingControl EnableCallbacks="False" ID="GridGroupingControl1"
runat="server" DataMember="DefaultView" DataSourceCachingMode="ViewState" AutoFormat="Office 2007 Blue"
BorderCollapse="Separate" GroupDropAreaCssClass="GridOffice2007BlueGroupDropArea" Width="750px">
For your convenience, we have prepared a simple sample to
demonstrate this and the same can be downloaded from the below link.
Sample: grouping.zip
Please let us know if you have any concerns.
Regards,
Hariharan J.V.