title: nuget doesn't recognize installed packages
body: <p>I have a C# project on Git that uses libraries from NuGet. Everything works fine, but when I pull on a fresh new machine and open the solution in Visual Studio it won't compile because of broken references. If I click on the references under the project I can see the classic warning sign with the yellow exclamation mark.</p>
  
  <p>Nuget restore won't do anything (and I still haven't found any use of this feature...), files repositories.config are fine. If I right click on solution and then 'Manage NuGet packages for solution' no installed package is shown.</p>
  
  <p>To this day I solved it this way: run</p>
  
  <pre><code>Install-Package package_name
  </code></pre>
  
  <p>it says:</p>
  
  <pre><code>'package_name' already installed.
  My_project already has a reference to 'package_name'.
  </code></pre>
  
  <p>...and after that it shows the packages on the Manager, already assigned to the correct project.</p>
  
  <p><br/>
  <strong>NOTHING HAS BEEN CHANGED in the code ANYWHERE</strong>, I can see that because there are no differences on Git.</p>
  
  <p>I have to do it only once on new machines, but it's <strong>really</strong> annoying. Any idea?</p>
  
  <p><br/>
  NuGet version: 2.8.60318.667</p>
  
  <p><br/>
  <strong>UPDATE</strong> 27/07</p>
  
  <p>I tried the procedure from scratch on another PC, with windows 10, and everything works... same version of Visual Studio, NuGet, etc... I'm baffled</p>