在希望这有助于他人：

在我们的例子中，这个问题是，我们在引用是为整个解决方案创建一个自定义的目标文件。尽管该项目得到更新，自定义目标文件被覆盖从而防止得到更新项目。

In our case, the issue was that we were referencing a custom targets file that was created for the entire solution. even though the project was getting updated, the custom targets file was overriding it thus preventing the project from getting updated.

更新目标文件指向.NET 4.5和一切细。

Updated the targets file to point to .net 4.5 and everything was fine.