Derived class in Python not being called by C# #1107

Hello - this is my first post so apologies if this is the wrong forum.

I'm trying to define a base class in C# and derive from that class in python / pythonnet. The C# class is very basic:

    public class Order
    {
        public string symbol;

        public virtual void Evaluate( Bar b )
        {
            Console.WriteLine( "from Order.Evaluate() - hello!" );
        }
    }

In python I have the specific order class defined as:

class LimitOrder(Order):

    def __init__(self):
        self.symbol = "SQ"


    def Evaluate( self, bar ):
        print( "LimitOrder.Evaluate() - yay python!" )

In C# I have an OMS class with a method: public void AddOrder( Order order )

When I pass in LimitOrder and call a method in the OMS that calls Evaluate, the Order class Evaluate method is called instead of the LimitOrder.Evaluate method.

I'm using python 3.6.7 and VS 2019 / .NET 4.7.2

In searching for this I'm only seeing 1 instance of a similar question being asked but no solid response. The Evaluate() method (and entire Order class for that matter) can be abstract but when I try that I get an error creating the LimitOrder object saying I can't create an abstract class.

Any help would be appreciated. Thanks in advance.