Ran into a funny one today. I was trying to debug my XF project and it wasn’t loading the symbols for the .NET Standard project so it was not hitting any of my breakpoints. I am currently using Visual Studio 2017.7.1. This was happening in my UWP project.
Obviously that’s not too helpful, but luckily I found some help in the Xamarin Forms as to the setting that was causing the problem. It has to do with the type of debugging information your build outputs. All I needed to do was change it to “Pdb-Only” and we were good to go.