We update our customer episerver 7.5 to 9.12. After that, categories property are "empty", selected values ( "Add one or more categories" ) is not show at all, just empty field. And same thing is all dropdowns where values come form categorys. Selected values are okay in currentpage and saving and publish work too..but selected values is missing?

    public class CourtSelectionFactory : ISelectionFactory
    {
        public IEnumerable GetSelections(ExtendedMetadata metadata)
        {
            var list = new List();
            var categoryRepository = EPiServer.ServiceLocation.ServiceLocator.Current.GetInstance();
            var root = categoryRepository.Get(Global.CategorySelectorRoots.ResolutionCategory_Court);
            if (root != null)
            {
                foreach (Category cat in root.Categories)
                {
                    list.Add(new SelectItem
                    {
                        Text = System.Net.WebUtility.HtmlDecode(cat.LocalizedDescription).ToUpper(),
                        Value = cat.ID
                    });
                }
            }
            return list;
        }
    }

    [EditorDescriptorRegistration(TargetType = typeof(string), UIHint = Global.UIHint.Court)]
    public class CourtSelector : EditorDescriptor
    {
        public override void ModifyMetadata(ExtendedMetadata metadata, IEnumerable attributes)
        {
            SelectionFactoryType = typeof(CourtSelectionFactory);

            ClientEditingClass = "epi-cms/contentediting/editors/SelectionEditor";

            base.ModifyMetadata(metadata, attributes);
        }
    }

Sorry bad english!