I had the same problem here (also using windows 8.1 and VS 2013)
To fix it you need to open in VS Tools | Options | Debugger | General and enable the flag [Use Managed Compatibility Mode], which essentially gives you the VS 2012 function evaluation behavior.
Reference:
http://weblog.west-wind.com/posts/2013/Nov/21/Visual-Studio-2013-Could-not-evaluate-Expression-Debugger-Abnormality