Hi Amit,
Thank you for your patience.
By default, when we apply the sorting for SfDataGrid, it does not sort the underlying DataTable collection. We have performed the sorting for DataTable in our source for bounded columns only. When you try to apply the sorting for Unbounded columns it does not work with DataTable collection. We did not provide the support for this.
Please let us know if you need further assistance on this.
Regards,
Susmitha S