New ASP.NET 8 Route tooling is not working (colorization and completion)

[mikadumont]

C# Extension Version: v2.0.46-beta.ge1f04155cf
C# Dev Kit Extension Version: v0.0.591-alpha

Steps to reproduce:

1. Install .NET 8 SDK

2. Open the attached solution (or create a new one but this has the use case)

3. Open program.cs and navigate to line 24 and edit code after "/books" and start typing:
   {bookId}
   EXPECT:
   New completion intellisense on the route.
   VS:
   

4. Complete the line of code as "/books/{bookId:int?}/{newParameter}"
   EXPECT: new colorization for route parameters
   Screenshot from VS:
   
   VSCode (note: tried multiple themes):
   

Feature: https://devblogs.microsoft.com/dotnet/aspnet-core-route-tooling-dotnet-8/

[JamesNK]

Customer request for this feature: dotnet/aspnetcore#47622