MudSelect Extended existing entries are not displayed.

[IngoManthey]

<MudSelectExtended T="CustomerWithEmail" ItemCollection="_customersWithEmail" SearchBox="true" SelectAllPosition="SelectAllPosition.BeforeSearchBox" SelectAllText=@Localizer["SelectAll"] SelectAll="true" MultiSelectionTextFunc="@GetMultiSelectionText" MultiSelection="true" @bind-SelectedValues="_options" Label=@Localizer["Customers"] AdornmentIcon="@Icons.Material.Filled.Search" AnchorOrigin="Origin.BottomCenter" ValuePresenter="ValuePresenter.Text" Clearable="true"> @foreach (var item in _customersWithEmail) { <MudSelectItemExtended T="CustomerWithEmail" Value="@item" Text="@item.CustomerName" /> } </MudSelectExtended>

(_options as HashSet)?.AddRange(data);

I load my existing data and set it to SelectedValues. The correct number is displayed in the text. However, when I open the selection, the existing entries are not displayed as selected.