Warning CS8032 occurs if the version of the Roslyn used by the C# compiler is older than the version used by the SonarC# analyzer. The latest version of the SonarC# analyzer requires Roslyn v1.3 or later.
The C# compiler is bundled with the MSBuild tools, so check the version of MSBuild you are using.
If you are building using the version of MSBuild bundled with Visual Studio then you need to be using Visual Studio 2015 Update 3 or later.
If you are building using a standalone version of MSBuild then you need MSBuild 15 (downloadable from https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2017).
Fixing that warning might also fix the last one (“Analyzer working directory does not exist”).