When a query is run In Microsoft Team Foundation Server 2012, only values needed for the display columns or the sort columns are returned with the work item. If your query doesn't include Changed Date as one of those columns, the connector can't determine correctly if the work item has changed.
To fix the problem using Team Explorer Everywhere, find the query in the Team Explorer view and choose View Results from the right-click menu. On the results page, right click on one of the column headers and choose Column Options. In the Column Options dialog, make sure the Changed Date column is selected in either the Fields or Sorting column lists.
To fix the problem using the Team Foundation Server web UI, find the query on the work items page and click on it. On the results tab, click on the Column Options link near the top. In the Column Options pop-up, make sure the Changed Date column is selected in either the display columns or sort columns lists.