Thank you for using syncfusion products,
We have analyzed the requirement and currently we don’t have a support for default segment selection at load time, however we have achieved this requirement in work around manner, please find the sample in the below location,
Please let us know if you have any further assistant.
Sorry about the inconvenience caused.
We have analyzed the reported issue with our sample, but we are unable to reproduce the issue. Could you please revert us by modifying the sample based on your application along with the replication procedure or is it possible for you to share you stack trace details with us?
This would be helpful for us to serve you.
Sorry for the inconvenience caused.
We have analyzed the stated issue with your code snippet. This issue can be fixed by accessing series from Chart as in below code snippet. Please let us know if you request further assistance on this.
Code snippet [C#]:
(this.columnChart.Series as CustomSelectableSeries).SegmentSelectedIndex = 2;