Hi Stanislav Perina,
Greeting from Syncfusion.
We have checked in your sample to reproduce the reported issue. but we are afraid that we are not able to reproduce the issue at our end.
So, could you please check the issue with the attached sample and let us know whether it is reproduced or not? If the issue was not reproduced, please revert us by modifying the sample based on your application along with replication procedure. This will be helpful for us to investigate further and provide you a better solution at the earliest. Please find the sample from the following location.
Output Screenshot:
Regards,
Ramya