Invalid cast and extensions at runtime

[americanslon]

Template

@{
    List<Domain.Comment.Comment> Comments = ViewBag.Comments;
    Domain.Lab.Lab Lab = ViewBag.Lab;
}

<div id="@("session" + Model.Id)">
    @(Model.Interval.GetAttribute<Common.Constants.CA.Interval.DescriptorAttribute>().Name)


    @foreach (var comment in Comments.OrderByDescending(x => x.CreatedDate))
    {
        <div class="header-small">@(comment.Author.DisplayName + " (" + comment.RolesDisplay + ")" + " on " + comment.CreatedDate.ToShortDateString() + " @ " + comment.CreatedDate.ToShortTimeString())</div>
        <div class="value">@comment.Text</div>
    }

    </div>
</div>

Compiles successfully, I also pass Common, Domain, System using AddAssemblyByName

Running the template

List<Domain.Comment.Comment> comments = new List<Domain.Comment.Comment>();
Domain.Lab.Lab Lab = new Domain.Lab.Lab();
string renderedTemplate = await RazorTemplating.LoadTemplate(Item, Config.GetValue<string>("AppSettings:Print:Templates:Session"), new
{
    Comments = comments,
    Lab = Lab
});

LoadTemplate is a wrapper around

private async Task<string> runTemplate<T>(T item, IRazorEngineCompiledTemplate<ViewBagRazorEngineTemplate> template, dynamic viewBag = null) => await template.RunAsync(instance =>
    {
        instance.Model = item;
        if (viewBag != null)
            instance.ViewBag = new AnonymousTypeWrapper(viewBag);
    });

Issue 1 - Invalid cast
List<Domain.Comment.Comment> Comments = ViewBag.Comments;
seems to cause
Cannot implicitly convert type 'System.Collections.Generic.List<object>' to 'System.Collections.Generic.List<Domain.Comment.Comment>'

Issue 2 -
@(Model.Interval.GetAttribute<Common.Constants.CA.Interval.DescriptorAttribute>().Name)
seems to cause
Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: 'Common.Constants.Session.CA.Interval.Intervals' does not contain a definition for 'GetAttribute'

GetAttribute is an extension method on the Enum. It's in the Common assembly. Here is the code

  public static T GetAttribute<T>(this Enum value) where T : Attribute
  {
      var type = value.GetType();
      var name = Enum.GetName(type, value);
      return type.GetField(name).GetCustomAttribute<T>();
  }

Any help would be appreciated. Thank you!