vscode-csharp: IntelliSense - Code suggestions are not working

Environment data

dotnet --info output: .NET Core SDK (gemäß “global.json”): Version: 3.1.200 Commit: c5123d973b

Laufzeitumgebung: OS Name: Windows OS Version: 10.0.18362 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\3.1.200\

Host (useful for support): Version: 3.1.2 Commit: 916b5cba26

.NET Core SDKs installed: 2.1.202 [C:\Program Files\dotnet\sdk] 2.1.403 [C:\Program Files\dotnet\sdk] 2.1.507 [C:\Program Files\dotnet\sdk] 2.1.509 [C:\Program Files\dotnet\sdk] 2.1.512 [C:\Program Files\dotnet\sdk] 2.2.203 [C:\Program Files\dotnet\sdk] 3.1.101 [C:\Program Files\dotnet\sdk] 3.1.200 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.All 2.2.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 2.2.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.1.16 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 2.2.4 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 3.1.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] VS Code version: 1.49.0 (User) C# Extension version: 1.23.2

OmniSharp log

Starting OmniSharp server at 14.9.2020, 17:32:46 Target: c:\Develop\ElectronNet

OmniSharp server started. Path: c:\Users\p. folster.KH.vscode\extensions\ms-dotnettools.csharp-1.23.2.omnisharp\1.37.1\OmniSharp.exe PID: 30048

    Starting OmniSharp on Windows 6.2.9200.0 (x64)

    DotNetPath set to dotnet

    Located 4 MSBuild instance(s)
        1: Visual Studio Professional 2019 16.5.29920.165 - "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin"
        2: Visual Studio Professional 2017 15.9.28307.1064 - "C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\MSBuild\15.0\Bin"
        3: Visual Studio Build Tools 2017 15.9.28307.1064 - "C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MSBuild\15.0\Bin"
        4: StandAlone 16.8.0 - "c:\Users\p. folster.KH\.vscode\extensions\ms-dotnettools.csharp-1.23.2\.omnisharp\1.37.1\.msbuild\Current\Bin"

    Registered MSBuild instance: Visual Studio Professional 2019 16.5.29920.165 - "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin"

    Detecting Cake files in 'c:\Develop\ElectronNet'.

    Could not find any Cake files

    No solution files found in 'c:\Develop\ElectronNet'

    Queue project update for 'c:\Develop\ElectronNet\ElectronNet.csproj'

    Detecting CSX files in 'c:\Develop\ElectronNet'.

    Could not find any CSX files

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.CSharpFormattingWorkspaceOptionsProvider, Order: 0

    Loading project: c:\Develop\ElectronNet\ElectronNet.csproj

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.Completion.CompletionOptionsProvider, Order: 0

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.RenameWorkspaceOptionsProvider, Order: 100

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.ImplementTypeWorkspaceOptionsProvider, Order: 110

    Invoking Workspace Options Provider: OmniSharp.Roslyn.CSharp.Services.BlockStructureWorkspaceOptionsProvider, Order: 140

    Configuration finished.

    Omnisharp server running using Stdio at location 'c:\Develop\ElectronNet' on host 28864.

    Miscellaneous file: c:\Develop\ElectronNet\Startup.cs added to workspace

    Successfully loaded project file 'c:\Develop\ElectronNet\ElectronNet.csproj'.

    Adding project 'c:\Develop\ElectronNet\ElectronNet.csproj'

    Update project: ElectronNet

Steps to reproduce

1. Load a folder that cointains a *.csproj file and *.cs files.
2. Open a *.cs file.
3. Display the intellisense menu by pressing ctrl + space.

Expected behavior

The intellisense menu shall show all available C# methods, properties, variables and so on.

Actual behavior

The intellisense menu shows only some “word completations”. It looks like the C# extension is not enabled. But the extension is working. There are syntax errors and so on shown.