Cannot get types from assembly after ReflectionOnlyLoadFrom

I have consulted code on the website http://codeproject.com with the title "Loading Assemblies from Anywhere into a New AppDomain" of Marius Bancila, but I tested the error as in the attached picture, currently, I don't know resolve, hope you help, thank you.

Link Code https://www.codeproject.com/Articles/453778/Loading-Assemblies-from-Anywhere-into-a-New-AppDom#_articleTop

Test

public class Program
{
    [STAThread]
    public static void Main()
    {
        var project = @"D:\Github\BeyConsPlugin\BeyConsProject\bin\x64\Debug\BeyConsRevitProject.dll";//Path to assembly
        var manager = new AssemblyReflectionManager();
        var success = manager.LoadAssembly(project, Guid.NewGuid().ToString());
        if (success)
        {
            var result = manager.Reflect(project, (a) =>
            {
                return a.GetTypes();
            });
            Console.WriteLine(string.Join("\n", result.Select(x => x.Name)));
        }            
        Console.ReadKey();
        manager.UnloadAssembly(project);
    }       
}

Error