DataFilter with Dropdown Troubles on DataList

I'm trying to follow the demo with the demo code:

 <RadzenDataFilterProperty TItem="Order" Property="OrderID" Title="Order ID" FilterValue="@selectedIds" 
                           Type="typeof(IEnumerable<int>)" FilterOperator="FilterOperator.Contains">
                            <FilterTemplate>
                                 <RadzenDropDown @bind-Value=@selectedIds Style="width:100%;"
                                    Change=@OnSelectedIdsChange Data="@(orderIds)" AllowClear="true" Multiple="true" />
                            </FilterTemplate>
                        </RadzenDataFilterProperty>

My implementation is:

 <RadzenDataFilterProperty TItem="BookGridVM" Property="SubGenres" Title="SubGenres" FilterValue="@_selectedSubgenres" 
                        Type="typeof(IEnumerable<string>)" FilterOperator="FilterOperator.Contains">
                    <FilterTemplate>
                            <RadzenDropDown @bind-Value=@_selectedSubgenres Style="width:100%;"
                            Change=@OnSelectedSubgenreChanged Data="@_subgenres" AllowClear="true" Multiple="true" />
                    </FilterTemplate>
                </RadzenDataFilterProperty>

In my code block, I have:

IEnumerable<string> _subgenres { get; set; } = new List<string>();
IEnumerable<string> _selectedSubgenres;

Subgenres in the BookGridVM is a string.

My on change event follows the demo as far as I can tell.

 void OnSelectedSubgenreChanged(object value)
    {
        if (_selectedSubgenres != null && !_selectedSubgenres.Any())
        {
            _selectedSubgenres = null;
        }
    }

I see the dropdown getting populated, but clicking a box doesn't filter the data set. For example in the screenshot below, if I clicked 'Action-Adventure', it should filter and show me at least the first object in the data list that has Action-Adventure listed as one of the subgenres. What am I missing to implement this?