Monotouch.Dialog: IElementSizing not being used

Question

I have a Custom element class that only resizes the rows when I rotate the device. On initial display the rows are not resized.

public class MultiImageElement : Element, IElementSizing

Which implements the IElementSizing interface:

    #region IElementSizing implementation
    public float GetHeight (UITableView tableView, NSIndexPath indexPath)
    {
        return 78;
    }
    #endregion

However, this is never called and the row heights remain the default size.

I add elements to my root in a loop:

for (int i = 0; i < secFolder.Rows; i++)
{
   sec.Add (new MultiImageElement (secFolder.ThumbnailPathsForRow (i), imageSize));
}
this.Root.Add (sec);