VS Code Intellisense for unity not working

The Intellisense for VS Code for Unity specific methods is not working. I keep getting the following warnings repeated several times in the Output log of VS Code:

[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.VSCode.Editor.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.TextMeshPro.Editor.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\UnityEngine.UI.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.Timeline.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.CollabProxy.Editor.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.Rider.Editor.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.TextMeshPro.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\UnityEditor.UI.csproj to be already loaded for project Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Expected project reference e:\GameDev\New Unity Project\Unity.Timeline.Editor.csproj to be already loaded for project Assembly-CSharp

The problem starts by saying:

[info]: OmniSharp.MSBuild.ProjectManager
        Adding project 'e:\GameDev\New Unity Project\Assembly-CSharp.csproj'
[info]: OmniSharp.MSBuild.ProjectManager
        Update project: Assembly-CSharp
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.Timeline.Editor.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.VSCode.Editor.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.TextMeshPro.Editor.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\UnityEngine.UI.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.Timeline.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.CollabProxy.Editor.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.Rider.Editor.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\Unity.TextMeshPro.csproj' for 'Assembly-CSharp'.
[warn]: OmniSharp.MSBuild.ProjectManager
        Unable to resolve project reference 'e:\GameDev\New Unity Project\UnityEditor.UI.csproj' for 'Assembly-CSharp'.

I have .NET v4.7.1 installed.

I have tried to generate the .csproj files by enabling this option in Unity: Edit > Preferences > External Tools > Generate all .csproj files.

I have also tried reinstalling all the VS Code extensions (using C# extension by microsoft, Debugger for Unity by Unity Technologies and Unity Code Snippets by Kleber Silva).

Any help would be highly appreciated.