I'm using ASP.NET Core template. I'm not sure this way will help you,because i'm programming beginner. But I'll show you how I do to debug.
1.Clone the source which you want to debug from GitHub.
2.Place source on a neighboring folder outside the solution.
3.Edit global.json like below.
{
"projects": [ "src", "test","../aspnetboilerplate-master/src" //This is example.Write your relative path.],
"sdk": {
"version": "1.0.0-preview2-003121"
}
}
Will this way help you?