Deploying to device fails for iOS project from VS2013

First post!

Since today, I can no longer deploy my Xamarin.iOS project to an actual device for both Debug and Release from Visual Studio 2013 Update 1. (I swear it was working yesterday, without code changes.) I'm using PCLs and am referencing various NuGet packages (Json.NET, MS BCL, Async and HTTP client, MvvmCross).

The build output is: 1>Server command 'Build': application remote build failed 1>Server failure while processing the command. See below for details 1>Response status: Error 1>error MT2002: Failed to resolve "System.Void System.Runtime.Versioning.TargetFrameworkAttribute::.ctor(System.String)" reference from "System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"

I'm running Xamarin.iOS 1.10.39

Deploying the same code revision to the same device from Xamarin Studio on the Mac works fine. Any ideas (besides giving up using Visual Studio)? Cheers!