Hi Katja,
Thank you for using Syncfusion products.
We are able to reproduce the reported issue at our side and suspect this could be a defect.
So we request you to open a new direct-trac incident with a excel file which reproduces the reported issue to proceed on this issue.So that we are able to log an Issue report and update with you with the patch for the reported issue fix.
Direct-Trac Link:
https://www.syncfusion.com/account/login?ReturnUrl=%2fsupport%2fdirecttrac%2fincidentsPlease let us know if you require any further clarifications.
Thanks,
Sridhar.S