Hi Yunus,
Greetings from Syncfusion.
We have considered your query as a bug and logged the defect report “Grouping - Expand/Collapse operations are not working with Virtualization” for the same. Thank you for taking the time to report this issue and helping us improve our product. At Syncfusion, we are committed to fixing all validated defects (subject to technological feasibility and Product Development Life Cycle) and will include the fix in our upcoming patch release which is expected to be rolled out on or before mid of March, 2022. Until then we appreciate your patience.
You can now track the current status of your request, review the proposed resolution timeline, and contact us for any further inquiries through this link.
Regards
Rahul