Unable to step over in WebStorm

I'm able to hit a breakpoint, inspect variables, etc., but when I click the "step over" button, it doesn't debug to the next line.  I just see "Frames are not available."  Right now I have the breakpoint at app.init().  Step into doesn't work, only force step into works.  I'm running Windows 8.1 and WebStorm 11.0.1.

    function createApplication() {
      var app = function(req, res, next) {
        app.handle(req, res, next);
      };
    
      mixin(app, EventEmitter.prototype, false);
      mixin(app, proto, false);
    
      app.request = { __proto__: req, app: app };
      app.response = { __proto__: res, app: app };
      app.init();
      return app;
    }