Describe the bug
One of my business objects has a List property. It appears to always be lost by the serializer - while my Create() method is RunLocal, the call to Insert() results in a null reference exception when the property is encountered. Even explicitly initializing and optionally setting a test value still results in a null.

The upgrading to v9 document seems to imply that List is explicitly supported?

Version and Platform
CSLA version: 9.0.0
OS: Windows
Platform: ASP.NET Core MVC

Code that Fails

public static readonly PropertyInfo<List<int>> AllowedPurposeIdsProperty = 
    RegisterProperty<List<int>>(c => c.AllowedPurposeIds);

public List<int> AllowedPurposeIds
{
    get => GetProperty(AllowedPurposeIdsProperty);
    set => SetProperty(AllowedPurposeIdsProperty, value);
}

Then the code that sets it:

var NewFolderObj = dataPortalFactory.GetPortal<FileFolder>().Create();
NewFolderObj.FolderName = entry.Name;
NewFolderObj.ModuleID = ModuleID;
NewFolderObj.GroupID = GroupID;
NewFolderObj.Deleted = false;
NewFolderObj.FolderOwnerID = FolderOwnerID;
NewFolderObj.AllowedPurposeIds = AllowedPurposeIds.ToList(); // stored locally as an array for annoying reasons

if (NewFolderObj.IsSavable)
{
    await NewFolderObj.SaveAndMergeAsync();
...

Stack Trace or Exception Detail
When I replaced the object with a string property, it works, but this is not ideal for type safety.

Additional context
Add any other context about the problem here.