Visual studio 2019 go to definition and Intellisense not working

Question

I have noticed a weird issue with Visual Studio 2019 v16.0.1 the IntelliSense about \"Using directive is unnecessary\" normally grey is missing and type reference suggestion

Answer 1

If you are facing this issue with Unity projects then,

1. Check in your Unity settings whether it has Visual Studio configured as the external editor.
2. Click on Regenarate project files in the Unity settings.
3. Go to Assets => Open C# project.

This will restart Visual Studio with your project.