Small glitch with datepicker. When using the time portion and 12 hour clock, the first time you hit the up or down, it does nothing. You have to click them a second time for them to work.
that is the AM/PM portion to clarify.
I was not able to reproduce this
I get that to work as well, it only happens when you bind to a property. In the instance I am working with I created a property called timeToday which has a value of DateTime.Now. When I use a datepicker set to timeonly 12 hour format hh:mm tt I get the issue. I have tested it in an empty page as well as a complex one. Same issue every time. If I don't bind it it works fine.
Which defeats the purpose of using it.
Ok, I see that your demo works fine. I created a form within Radzen Studio, I added a datepicker to it, set it to time only, bound it to a property (timeToday which is a DateTime.Now), gave it a format of hh:mm tt, turned on the ok button, set it to 12 hour format. When I run it, the AM/PM up down does not work on the first click.
Here is the generated code (not touched by me)
<div class="align-items-center d-flex col-md-6" style="padding-bottom: 5px; padding-right: 5px">
<RadzenDatePicker AllowClear="false" DateFormat="hh:mm tt" HourFormat="12" Placeholder="Time In" PopupRenderMode="PopupRenderMode.Initial" ShowTime="true" ShowTimeOkButton="true" style="width: 100%" TimeOnly="true" @bind-Value="@timeToday" Name="Datepicker2" class="my-timeonly-datepicker">
</RadzenDatePicker>
</div>
Please use Radzen Studio to create a page and set up the control this way and see if it works for you.
Thanks for the help.
the class only changes the datepicker icon to a clock. If I remove it, I get the same behavior as before.
Radzen will just generate the code - it does not matter if the component is setup using Radzen or manually. What version of Radzen.Blazor is referenced in your project? Your markup also worked normally on my end:

Any additional info? Different culture in your application?
I am on the latest update of Radzen. I also created a test application with nothing more than a page with a datepicker on it. In the test application I used the standard theme. I do not know why this is happening. I can make the am/pm work as long as I don't bind a value.
Can you possibly try to duplicate it the way that I am without using your demo? Just create a test application, with one page with only a datepicker on it? Set the datepicker the way I have discussed and see if it works for you?
I've tested using your instruction and here is the result:
I've retested also your report from July and I was not able to reproduce the wrong behavior reported at that time.
Here is the application:
Ok...uninstalled and re-installed Radzen and now works fine!