KeywordQuery problem

Question

Can anyone help me with SharePoint 2010 KeywordQuery problem? I have the following code to search user profile and sort results by managed property.

            var keywordQuery = new KeywordQuery(site)
            {
                QueryText = "",
                KeywordInclusion = KeywordInclusion.AllKeywords,
                HiddenConstraints = "scope:" + "\"People\"",
                ResultTypes = ResultType.RelevantResults,
                RankingModelId = "D9BFB1A1-9036-4627-83B2-BBD9983AC8A1"
            };

            keywordQuery.EnablePhonetic = true;
            keywordQuery.EnableNicknames = true;
            keywordQuery.ResultsProvider = SearchProvider.SharepointSearch;

            keywordQuery.SortList.Add("WorkEmail", SortDirection.Ascending);

            keywordQuery.SelectProperties.Add("PreferredName");
            keywordQuery.SelectProperties.Add("AccountName");
            keywordQuery.SelectProperties.Add("OrganizationDepartment");
            keywordQuery.SelectProperties.Add("UserFirstName");
            keywordQuery.SelectProperties.Add("UserLastName");
            keywordQuery.SelectProperties.Add("UserSurName");

            ResultTableCollection resultTableCol = keywordQuery.Execute();
            ResultTable resultTable = resultTableCol[ResultType.RelevantResults];

When I use WorkEmail as the property to sort by everithing is working as I expect. But when I replace WorkEmail with say JobTitle sorting does not work. It works as if sort list passed to KeywordQuery is empty. My view is that something wrong with managed properties metadata. MaxCharactersInPropertyStoreIndex = 64 for both mentioned properties