Tracking the current version of StyleCop is a bit awkward. Last week I got an automated email from CodePlex saying 4.7.52.0 had been released . I thought this was the most up to date version, so upgraded my StyleCop command line wrapper and my VSTS StyleCop task from 4.7.47.0 to 4.7.52.0.
However, I was wrong about the current version. I had not realised that the StyleCop team had forked the code onto GitHub. GitHub is now the home of the Visual Studio 2015 and C# 6 development of StyleCop, while Codeplex remains the home of the legacy Visual Studio versions. I had only upgraded to a legacy patch version, not the current version.
So I upgraded my StyleCop Command Line tool and my VSTS StyleCop task to wrapper 4.7.59.0, thus I think bringing me up to date.