Hi Edmund,
Thank you for contacting Syncfusion support.
We are unable to reproduce the issue at our end but we have created a sample with your code example. Please share the following information to find the cause of the issue.
1. Is there any script error or exception thrown in your project? If so, attach a screenshot of your stack trace.
2. Share the video to show the issue.
3. Essential studio version details.
4. Browser details.
5. Issue replication procedure.
6. Attach screenshot of the POST request in Network tab of browser developer tool. Please expand the post request and share the screenshot
7. An issue reproducing sample if possible or replicate the issue in the following sample.
Regards,
Jayaprakash K.