On a fresh installation of Visual Studio 2015 I created an Android application and Android native library. Functions from native library are referenced in the app code through D
I had the same problem and I think I've figured it out.
The Xamarin debugger can only debug managed (i.e. C#) code. Breakpoints only work with the Xamarin debugger if the project being debugged is a managed project. They don't work if the project is a native app or native library.
The Microsoft debugger can only debug native (i.e. C/C++) code. Breakpoints only work with the Microsoft debugger if the project being debugged is a native app or native library, or if it is attached to an already-running Android process.
I've been able to use both debuggers simultaneously to debug a hybrid (managed+native) app, by following this procedure:
I made a short video to demonstrate this: Android debugging managed and native code using Visual Studio 2015
The tip described in this post solved my problem:
https://blogs.msdn.microsoft.com/cesardelatorre/2016/02/06/solving-issue-with-vs-android-emulator-xamarin-apps-and-intel-skylake-processor-i-e-when-using-a-microsoft-surface-book-i7-surface-pro-4-etc/
SOLUTION:
And we were right! The issue is related to Hyper-V on Windows 10 when running on the latest Intel (Skylake) processors. (Thanks Mike, from the VS Android Emulator team, who suggested this possible workaround).
Hot to Fix it:
You can see below the checkbox you have to select.