We're using the DatePicker TimeOnly component to let the user select a start and end time.
After selecting the time and hitting the OK button of your popup an NullReferenceException is logged:
Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: Object reference not set to an instance of an object.
System.NullReferenceException: Object reference not set to an instance of an object.
at Radzen.Blazor.RadzenDatePicker`1.<<BuildRenderTree>b__0_7>d[[System.DateTime, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle)
The same happens on your demo page: https://blazor.radzen.com/datepicker
My question looks like this post as well: RadzenDatePicker - TimeOnly Error