Angular2 PreRendering not working correctly when base href set to subdirectory

[alterius]

I'm trying to make PreRendering work with an Angular2 app based in a subdirectory.

Steps to recreate:

1. Created a new project from the Microsoft SPA Templates dotnet new angular -n DashboardTest (dotnet new --install Microsoft.AspNetCore.SpaTemplates::* to install the templates package)
2. Removed all routing from Startup.cs and replaced with app.UseMvc();. This means that only routes I've explicitly defined will be mapped.
3. Added [Route("/dashboard/{*angularRoute}")] attribute to the Index() action on the HomeController to catch all requests to my chosen subdirectory of /dashboard and pre-render the angular app (the Home/Index view already contains <app asp-prerender-module="ClientApp/dist/main-server">Loading...</app> for pre-rendering.)
4. Updated the base href tag in _Layout.cshtml to <base href="/dashboard" /> to correctly configure the angular app to treat /dashboard as it's root.

On the surface everything appears to work beautifully, however behind the scenes the pre-rendering has broken. To prove this, load view-source:http://localhost:5000/dashboard/counter (in Chrome) - you'll see the rendered output is actually the /home route, not the /counter route as expected.

Suggested fix:
Add public string BaseHref { get; set; } and unencodedPathAndQuery = !string.IsNullOrEmpty(BaseHref) && unencodedPathAndQuery.StartsWith(BaseHref) ? unencodedPathAndQuery.Substring(BaseHref.Length) : unencodedPathAndQuery; to PrerenderTagHelper

[ADefWebserver]

This is the fix that is already in the Dev branch that should address the issue:
#961 (comment)

[alterius]

#961 appears to solve a problem with the Angular app root directory - this isn't an issue for me. It's the pre-rendering that's not working correctly.

[SteveSandersonMS]

There are indeed some known issues with workarounds. Please see #488 and #571.

Closing this one as duplicate.