Error: Your project file doesn't list 'win' as a "RuntimeIdentifier". You should add 'win' to the "RuntimeIdentifiers" property in your project file and then re-run NuGet restore.
Clean your solution
Close Visual Studio
Delete obj & bin folders using Powershell command:
Get-ChildItem .\ -include bin,obj -Recurse | foreach { remove-item $_.fullname -Force -Recurse }
Delete the .vs folder (optional, if you get red lines but it builds OK)
Re-open Visual Studio
Re-build all