Radzen Popup appears at the bottom of the page

I'm using the Radzen Popup component but the popup content appears at the bottom of the page below the footer.

This is my code below:

<RadzenButton @ref=button Text="Pop Up" Click="@(args => popup.ToggleAsync(button.Element))" /><Popup @ref=popup Lazy="true" Open="@OnOpen"><RadzenStack Orientation="Orientation.Vertical"><RadzenButton Text="tes1" /><RadzenButton Text="tes2" /></RadzenStack></Popup>@code {    RadzenButton button;    private Popup popup;    async Task OnOpen()    {        await JSRuntime.InvokeVoidAsync("eval", "setTimeout(function() {}, 200)");    }}

I'm using server-side render mode. Does anyone know what did I miss here?