Interesting: with build log Level = "Normal", I found an interesting info (first line):
1> No way to resolve conflict between "System.ValueTuple, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" and "System.ValueTuple, Version=0.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51". Choosing "System.ValueTuple, Version=4.0.1.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" arbitrarily.
1> Consider app.config remapping of assembly "Microsoft.CodeAnalysis, Culture=neutral, PublicKeyToken=31bf3856ad364e35" from Version "2.9.0.0" [] to Version "3.4.0.0" [C:\Temp\AlterNET Studio v.6_modified\Demo\packages\Microsoft.CodeAnalysis.Common.3.4.0\lib\netstandard2.0\Microsoft.CodeAnalysis.dll] to solve conflict and get rid of warning.
1> Consider app.config remapping of assembly "System.Collections.Concurrent, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" from Version "4.0.10.0" [C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\Facades\System.Collections.Concurrent.dll] to Version "4.0.11.0" [C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\lib\System.Collections.Concurrent.dll] to solve conflict and get rid of warning.
,...
This is followed by a lot of other "Consider app.config remapping..." hints, but the "System.ValueTuple.dll" seems to be the issue.
You provide 4.0.2.0, and I have installed the same Version in C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\MSBuild\Microsoft\Microsoft.NET.Build.Extensions\net461\lib
Best regards
Wolfgang