Hi Francois,
Greetings from Syncfusion support.
We have checked your query and we have confirmed it as a bug and logged the defect report “Exception throws while performing Grouping operation with foreign key field value as null” 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 including the defect fix in our upcoming bi-weekly release which is expected to be rolled on or before mid of June, 2021.
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.
Until then we appreciate your patience.
Regards,
Jeevakanth SP.