title: VSCode intellisense not working for one c# project under the solution
body: <p>I have  just installed VS Code on my Mac and installed OmniSharp to work with dotnet Core and C# applications. I did get code from GitHub, which used to have no issues. However it is having following issues right now:</p>
  
  <ol>
  <li>I have multiple projects in a solution</li>
  <li>Dotnet build from solution does not show any errors on one particular project. However, if I go to the folder containing the problem project and then do <code>dotnet build</code> on that particular project then it does actually show errors. Before this problem, doing doenet build at solution level will show me all the errors in all the projects including this one.</li>
  <li>Also, when I am looking at the file which does have issues, the code whcih clearly have isssues, does not show any red-lines under it.</li>
  <li>Intellisense also stopped working. In any file of this particular project I cannot go to any item > Right click and go to definition. It just does not work anymore. </li>
  </ol>
  
  <p>I have tried deleting bin and obj folders and rebuilding the project but it does not seem to be working. Anything else that I can try?</p>