.NET Core: COM delegate throws System.AccessViolationException when trying to call 32-bit dllhost from 64-bit application

Question

I need to pass a delegate function between .NET 6 32.bit COM server and .NET 6 64.bit client to communicate. I wrote a sample with a 32-bit server, implemented as a C# class in a class library project, hosted by Windows system surrogate and a 64-bit client that calls the server.

Class code:

namespace OutOfProcCOM;

[ComVisible(true)]
[Guid(Contract.Constants.ServerInterface)]  //F586D6F4-AF37-441E-80A6-3D33D977882D
public interface IServer
{
    double Test();

    void TestEvent([MarshalAs(UnmanagedType.FunctionPtr)] ChangeDelegate d);
}

[ComVisible(true)]
[Guid(Contract.Constants.ServerInterface)]  //F586D6F4-AF37-441E-80A6-3D33D977882D
public delegate bool ChangeDelegate();


[ComVisible(true)]
[Guid(Contract.Constants.ServerClass)]  //"AF080472-F173-4D9D-8BE7-435776617347"
public sealed class DllServer : IServer
{
    public event OnMyEventDelegate OnMyEvent;

    public double Test()
    {
        return 10;
    }

    public void TestEvent([MarshalAs(UnmanagedType.FunctionPtr)] ChangeDelegate d)
    {
       d?.Invoke();
    }
}

This is how I register it:

regsvr32.exe "DllServer.comhost.dll"

Registry entry

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Wow6432Node\AppID\{AF080472-F173-4D9D-8BE7-435776617347}]
"DllSurrogate"=""

[HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{AF080472-F173-4D9D-8BE7-435776617347}]
"AppID"="{AF080472-F173-4D9D-8BE7-435776617347}"

And here is the client:

var type = Type.GetTypeFromProgID("OutOfProcCOM.DllServer");
var obj = (IServer)Activator.CreateInstance(type);

var x = obj.Test();

obj.TestEvent(() => {
   Console.WriteLine("Hello!");
});

Execution of obj.Test() is working. Execution of obj.TestEvent(...) throws a System.AccessViolationException:

System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

Is there someone who can help me? I am going crazy migrating a COM application to .NET Core!

Thank you!