Blazor StateHasChanged() Not Updating Child Components

I have a Service that contains a catalog of items. The items depends on the Service's active company.

// Tell Service to refresh in context of Company 1await Service.SetActiveCompany(1);// Get Catalog (which will be in the context of Company 1)Catalog catalog = Service.Catalog;// Tell Service to refresh in context of Company 2await Service.SetActiveCompany(2);// Get Catalog (which will be in the context of Company 2)catalog = Service.Catalog;

The above works fine in isolation. The Catalog is refreshed with items from the appropriate company.

In my app I have a Layout that includes dropdown to select active company. When this changes I call:

await Service.SetActiveCompany(dropdown.selectedCompanyId);

In the Service, I refresh the catalog and raise an event

public class CompanyChangedEventArgs : EventArgs { }public class Service{    public event EventHandle<CompanyChangedEventArgs> CompanyChanged;    protected void OnCompanyChanged()         => CompanyChanged?.Invoke(this, new CompanyChangedEventArgs());    public Catalog Catalog { get; private set; }    public async Task SetActiveCompany(int companyId)    {        Catalog = await API.GetCatalogForCompany(companyId);        OnCompanyChanged();    }}

In a parent component (using the layout above) I catch the event

<CatalogSectionA /><CatalogSectionB />@code {   protected override void OnInitialized()   {       Service.CompanyChanged += HandleCompanyChanged;       base.OnInitialized();   }   HandleCompanyChanged(object sender, EventArgs e) => StateHasChanged();}

I expect this to cause CatalogSectionA and CatalogSectionB components to refresh.

CatalogSectionA

<div>  @foreach (Item i in Catalog.SectionA.Items)  {<div>@i.Name</div>  }</div>@code {  Catalog Catalog => Service.Catalog;}

CatalogSectionB

<div>  @foreach (Item i in Catalog.SectionB.Items)  {<div>@i.Name</div>  }</div>@code {  Catalog Catalog => Service.Catalog;}

I had expected calling StateHasChanged() in the parent component to force re-render of CatalogSectionA and CatalogSectionB, but they are not.

I could put a Refresh method on each and call those from parent when company change event is handled, but I thought that would not be necessary with Blazor and StateHasChanged() would do the trick?