I found a small bug in radzen, using the example you taught in the post form losing value
I used the formData to set, but in doing so the Data field, which was being set automatically, loses its value when starting the page.
Below prints of the demo
How i am setting the date:
How is in the form (case I leave the "Date" with nothing will normally run as I will show below, but will return the error of the post I said above, if I put as "FormData", it loses the value of the date field, as I will show below):