Using Visual Studio 2017, any coding error results in "The application is in break mode"

Take the following code:
var x = new List();
var y = x[3];

When debugging a UWP project, Visual Studio stops on the offending line and produces the expected error: "System.ArgumentOutOfRangeException: 'Index was out of range..."

Using the same solution, Android or iOS project, instead of breaking on the incorrect code, Visual Studio displays the "Break Mode" tab with "The application is in break mode". The Exception details only state "An unhandled exception occurred"

Anyone have any idea how to get Visual Studio to break on the offending line?