Trying to add Blazor Server to an `Area` in an existing Razor Pages app

// _Host.cshtml
@page "/Admin/{**segment}"
@using Ogma3.Areas.Admin.Pages.Shared

@{
    Layout = "_Layout";
}

<app>
    @(await Html.RenderComponentAsync<App>(RenderMode.Server))
</app>

<!-- App.razor -->
<Router AppAssembly="typeof(Program).Assembly">
    <Found Context="routeData">
        <RouteView RouteData="routeData"/>
    </Found>
    <NotFound>
        <h1>Page not found</h1>
        <p>Sorry, but there's nothing here!</p>
    </NotFound>
</Router>

<script src="~/_framework/blazor.server.js"></script>