Hmm guess the button was indeed for a wrong SDK. The link you provided seems to have solved the ‘SDK cannot be located’ error.
I do still keep getting this one:
Clicking the ‘Show Output’ button gives me this:
Loading project: c:\Users\Xavier\Documents\UnityProjects\Obstacle Course\Assembly-CSharp.csproj
[fail]: OmniSharp.MSBuild.ProjectLoader
The reference assemblies for .NETFramework,Version=v4.7.1 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks
[warn]: OmniSharp.MSBuild.ProjectManager
Failed to load project file 'c:\Users\Xavier\Documents\UnityProjects\Obstacle Course\Assembly-CSharp.csproj'.
c:\Users\Xavier\Documents\UnityProjects\Obstacle Course\Assembly-CSharp.csproj
c:\Users\Xavier\.vscode\extensions\ms-dotnettools.csharp-1.23.9\.omnisharp\1.37.8-beta.15\.msbuild\Current\Bin\Microsoft.Common.CurrentVersion.targets(1216,5): Error: The reference assemblies for .NETFramework,Version=v4.7.1 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks
[fail]: OmniSharp.MSBuild.ProjectManager
Attempted to update project that is not loaded: c:\Users\Xavier\Documents\UnityProjects\Obstacle Course\Assembly-CSharp.csproj