Hello, Peter,
Thank you for the clarification.
I saw that there was a ticket submit with a similar issue.
Indeed this will require an enhancement from our side as currently, the groups created by the process method are not unique. Currently, there are two options:
1) The one shown in the example, where the issue is that two groups with the same value will be both expanded and collapsed.
2) Using index instead of value, the issue with that approach is that if we sort or filter the data, a different group may be on that index.
We are searching for a third option that will eliminate the issue of both approaches.
We have logged here and I will post the link, so if anyone else has the same issue they can follow it and share ideas:
https://github.com/telerik/kendo-react/issues/500
Regards,
Stefan
Progress Telerik
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