C# NET 5.0 source generator basic example is not generating output

I am copying everything as closely as I can from the Microsoft website example but nothing is generating. I created a MCVE to try to find out why the following error happens:

Warning CS8034  
Unable to load Analyzer assembly C:\Users\me\source\repos\SourceGenTest\SourceGenerators\bin\Debug\netstandard2.0\SourceGenerators.dll: 
Could not find file 'C:\Users\me\source\repos\SourceGenTest\SourceGenerators\bin\Debug\netstandard2.0\SourceGenerators.dll'.
SourceGenLibrary        1   Active

I have checked the path provided, and SourceGenerators.dll exists. The error makes no sense to me.

Note: In the MCVE I provided, apparently there's no build warnings. Not sure why, but there's still no output from the source generator.

My goal is to have a workflow like:

SourceGenerators (class library)
    is consumed by
        SourceGenLibrary (class library)
            is consumed by
                SourceGenConsole (Console project)

Whereby I want an analyzer to generate definitions in a class library that will be shared among many projects. The above workflow reduces it to one project depending on one library which depends on the source generators to keep this as MCVE-as-possible.

Because copying all of this stuff, is annoying, here's an upload link if you're lazy: Download link MCVE (expires a week after posting supposedly, but the source is below).

Relevant info:

$ dotnet --version
5.0.201

$ dotnet --list-sdks
5.0.103 [C:\Program Files\dotnet\sdk]
5.0.201 [C:\Program Files\dotnet\sdk]

These are the source files and what they contain.

/SourceGenTest.sln

Microsoft Visual Studio Solution File, Format Version 12.00
# Visual Studio Version 16
VisualStudioVersion = 16.0.31112.23
MinimumVisualStudioVersion = 10.0.40219.1
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SourceGenLibrary", "SourceGenLibrary\SourceGenLibrary.csproj", "{8702B80A-ACA3-4546-BBE8-A9FEE686A758}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SourceGenerators", "SourceGenerators\SourceGenerators.csproj", "{D693D3B2-F981-4D6D-AC97-B8C636E8C5C0}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SourceGenConsole", "SourceGenConsole\SourceGenConsole.csproj", "{3730848C-847C-4DF9-A0B3-5ADB5FE9D1E0}"
EndProject
Global
    GlobalSection(SolutionConfigurationPlatforms) = preSolution
        Debug|Any CPU = Debug|Any CPU
        Release|Any CPU = Release|Any CPU
    EndGlobalSection
    GlobalSection(ProjectConfigurationPlatforms) = postSolution
        {8702B80A-ACA3-4546-BBE8-A9FEE686A758}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
        {8702B80A-ACA3-4546-BBE8-A9FEE686A758}.Debug|Any CPU.Build.0 = Debug|Any CPU
        {8702B80A-ACA3-4546-BBE8-A9FEE686A758}.Release|Any CPU.ActiveCfg = Release|Any CPU
        {8702B80A-ACA3-4546-BBE8-A9FEE686A758}.Release|Any CPU.Build.0 = Release|Any CPU
        {D693D3B2-F981-4D6D-AC97-B8C636E8C5C0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
        {D693D3B2-F981-4D6D-AC97-B8C636E8C5C0}.Debug|Any CPU.Build.0 = Debug|Any CPU
        {D693D3B2-F981-4D6D-AC97-B8C636E8C5C0}.Release|Any CPU.ActiveCfg = Release|Any CPU
        {D693D3B2-F981-4D6D-AC97-B8C636E8C5C0}.Release|Any CPU.Build.0 = Release|Any CPU
        {3730848C-847C-4DF9-A0B3-5ADB5FE9D1E0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
        {3730848C-847C-4DF9-A0B3-5ADB5FE9D1E0}.Debug|Any CPU.Build.0 = Debug|Any CPU
        {3730848C-847C-4DF9-A0B3-5ADB5FE9D1E0}.Release|Any CPU.ActiveCfg = Release|Any CPU
        {3730848C-847C-4DF9-A0B3-5ADB5FE9D1E0}.Release|Any CPU.Build.0 = Release|Any CPU
    EndGlobalSection
    GlobalSection(SolutionProperties) = preSolution
        HideSolutionNode = FALSE
    EndGlobalSection
    GlobalSection(ExtensibilityGlobals) = postSolution
        SolutionGuid = {A3752997-47E1-4086-87C8-1583B5E0EDF1}
    EndGlobalSection
EndGlobal

/SourceGenerators/SourceGenerators.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
    <LangVersion>preview</LangVersion>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.2" />
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.9.0" />
  </ItemGroup>

</Project>

/SourceGenerators/Class1.cs

using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Text;

namespace SourceGeneratorSamples
{
    [Generator]
    public class HelloWorldGenerator : ISourceGenerator
    {
        public void Execute(GeneratorExecutionContext context)
        {
            // begin creating the source we'll inject into the users compilation
            var sourceBuilder = new StringBuilder(@"
            using System;
            namespace HelloWorldGenerated
            {
                public static class HelloWorld
                {
                    public static void SayHello() 
                    {
                        Console.WriteLine(""Hello from generated code!"");
                        Console.WriteLine(""The following syntax trees existed in the compilation that created this program:"");
            ");

            // using the context, get a list of syntax trees in the users compilation
            var syntaxTrees = context.Compilation.SyntaxTrees;

            // add the filepath of each tree to the class we're building
            foreach (SyntaxTree tree in syntaxTrees)
            {
                sourceBuilder.AppendLine($@"Console.WriteLine(@"" - {tree.FilePath}"");");
            }

            // finish creating the source to inject
            sourceBuilder.Append(@"
                    }
                }
            }");

            // inject the created source into the users compilation
            context.AddSource("helloWorldGenerator", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));
        }

        public void Initialize(GeneratorInitializationContext context)
        {
        }
    }
}

/SourceGenLibrary/SourceGenLibrary.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <LangVersion>preview</LangVersion>
    <AssemblyName>SourceGenLibrary</AssemblyName>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\SourceGenerators\SourceGenerators.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
  </ItemGroup>

</Project>

/SourceGenLibrary/Class1.cs

using System;

namespace SourceGenTest
{
    public class Class1
    {
        public static void Func()
        {
            //HelloWorldGenerator.HelloWorld.SayHello();
        }
    }
}

/SourceGenConsole/SourceGenConsole.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <LangVersion>preview</LangVersion>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\SourceGenLibrary\SourceGenLibrary.csproj" />
  </ItemGroup>

</Project>

/SourceGenConsole/Program.cs

using System;

namespace SourceGenConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
        }
    }
}