Why is MEF in dotnet 6 using ImportManynot working based on code that worked in dotnet framework 4.6.2

Question

I am converting code from dotnetframework to a dotnet6 WPF Hybrid app, and use MEF. The compose show the plugin and metdata in the container but neither collection via [ImportMany] have any contents. I get no exceptions. The plugins do load in a DotnetFramework app. has anyone any ideas on getting ImportMany to work?

public class PluginHandler
[ImportMany(typeof(IKapprisWebViewerClientPlugin))]
        private static IEnumerable<Lazy<IKapprisWebViewerClientPlugin, IKapprisWebViewerClientPluginData>>? plugins { get; set; } = new 
List<Lazy<IKapprisWebViewerClientPlugin, IKapprisWebViewerClientPluginData>>();

        [ImportMany(typeof(IKapprisWebViewerClientPlugin))]
        private static IEnumerable<IKapprisWebViewerClientPlugin>? plugins1 { get; set; } = new List<IKapprisWebViewerClientPlugin>();

 public PluginHandler()
        {
            //An aggregate catalog that combines multiple catalogs
            var catalog = new AggregateCatalog();

            string exePath = System.Reflection.Assembly.GetExecutingAssembly().Location;
            string directory = new Uri(Path.GetDirectoryName(exePath)).LocalPath;

            //Adds all the parts found in all assemblies in 
            //the same directory as the executing program
            catalog.Catalogs.Add(
             new DirectoryCatalog(
              directory, "kwc*.dll"));

            //Create the CompositionContainer with the parts in the catalog
            CompositionContainer container = new CompositionContainer(catalog);

            //Fill the imports of this object
            container.ComposeParts(this);
            //container.SatisfyImportsOnce(this);

        }
}

the plugin class

    [Export(typeof(IKapprisWebViewerClientPlugin))]
    [ExportMetadata("Name", "IManage 10 / Cloud")]
    public class WebViewerIntegration : WebViewerClientPlugin
    {
     ...
    }

 public interface IKapprisWebViewerClientPluginData
    {
        /// <summary>
        /// Name used to identify plugin
        /// </summary>
        string Name { get; }
    }