Environment

• Pythonnet version:3.0.0.0
• Python version:3.9
• Operating System: Windows 10, 64 bits
• .NET Runtime: Mono, .Net Standard 2.0
• Unity: 2020.3.11

Details

• Describe what you were trying to get done.

  I trying to create a plugin architecture with pythonnet that allows async callbacks (for example, to wait a server response)

  I have been able to pass a delegate from python to c#. Then, the c# code calls the delegate, which points to python again. This is working just fine.
  The problem is when I try to do this, through a unity co-routine. When I try that, I get the a PyScopeException: object is not a module (see traceback section)
  In summary;
  Python -> delegate -> c# -> callback-> python. Working fine
  Python -> delegate -> c# -> Unity coroutine -> callback-> python. PyScopeException: object is not a module

• What commands did you run to trigger this issue? If you can provide a
  Minimal, Complete, and Verifiable example
  this will help us understand the issue.

This code reproduces exactly the issue.

using Python.Runtime;
using System;
using System.Collections;
using UnityEngine;

public class EventTest : MonoBehaviour
{
    public enum Mode
    {
        SimpleCallback,
        CoroutineCallback
    }

    public Mode mode = Mode.CoroutineCallback;

    void Start()
    {
        Test();
    }

    private void Test()
    {
        PythonEngine.Initialize(mode:ShutdownMode.Soft);
        using (Py.GIL())
        {
            PyScope scope = Py.CreateScope();
            SetupLogger(scope);
            scope.Set("callbackTest", this.ToPython());

            var code = string.Empty;
            if (mode == Mode.SimpleCallback)
            {
                code = GetCodeForSimpleCallback();//Working
            }
            else
            {
                code = GetCodeForCoroutineCallback();//not working, PyScopeException: object is not a module
            }

            var pyCompile = PythonEngine.Compile(code);
            scope.Execute(pyCompile);
        }

        PythonEngine.Shutdown(mode: ShutdownMode.Soft);
    }

    private string GetCodeForSimpleCallback()
    {
        string code =
@"
from System import Action

def PrintText(text):
    print(text)

callback = Action[str](PrintText)
callbackTest.Test(callback)
";

        return code;
    }

    private string GetCodeForCoroutineCallback()
    {
        string code =
@"
from System import Action

def PrintText(text):
    print(text)

callback = Action[str](PrintText)
callbackTest.TestCallbackWithCoroutine(callback)
";

        return code;
    }

    public void Test(Action<string> func)
    {
        func("Test");
    }

    public void TestCallbackWithCoroutine(Action<string> func)
    {
        StartCoroutine(ICallback(func));
    }

    private IEnumerator ICallback(Action<string> func)
    {
        yield return new WaitForSeconds(1f);
        func("Test Coroutine Callback");
    }


    #region miscellaneous

    private void SetupLogger(PyScope scope)
    {
        scope.Set("Logger", this.ToPython());

        string loggerSrc = 
            "import sys\n" 
            + "sys.stdout = Logger\n";
        scope.Exec(loggerSrc);
    }

    public void write(string line)
    {
        Debug.Log(line);
    }
    #endregion
}

• If there was a crash, please include the traceback here.

PyScopeException: object is not a module
Python.Runtime.PyScope..ctor (System.IntPtr ptr, Python.Runtime.PyScopeManager manager) (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/pyscope.cs:61)
Python.Runtime.PyScope..ctor (Python.Runtime.NewReference& reference, Python.Runtime.PyScopeManager manager) (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/pyscope.cs:48)
Python.Runtime.PyModule..ctor (Python.Runtime.NewReference& reference) (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/pymodule.cs:7)
Python.Runtime.PyModule.Import (System.String name) (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/pymodule.cs:19)
Python.Runtime.PythonException..ctor () (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/pythonexception.cs:51)
Python.Runtime.Dispatcher.TrueDispatch (System.Object[] args) (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/delegatemanager.cs:299)
Python.Runtime.Dispatcher.Dispatch (System.Object[] args) (at C:/Users/mespino/Workspace/Cityzenith/Pythonnet/src/runtime/delegatemanager.cs:269)
__System_Action`1/[/[System_String/, mscorlib/, Version=4_0_0_0/, Culture=neutral/, PublicKeyToken=b77a5c561934e089/]/]Dispatcher.Invoke (System.String ) (at <16ca6f0fe1de48349722972d141afb2e>:0)
EventTest+d__8.MoveNext () (at Assets/Event/EventTest.cs:92)
UnityEngine.SetupCoroutine.InvokeMoveNext (System.Collections.IEnumerator enumerator, System.IntPtr returnValueAddress) (at <127e81e1cb3441cc97d26b1910daae77>:0)

    print('TODO')