title: #DATASYNC not disappearing after fixing merge
body: <p>I have a report with 4 query's.
  I used two of them in my report.
  I merged two of them in a report and the report runs fine.
  However, if a change anything in the merge (eg. add another dimension to the merge or unmerge) the report only shows #Datasync.</p>
  
  <p>If I repair the merge <strong>as it was</strong>, the report <strong>still</strong> shows #Datasync. how is that possible?</p>
  
  <p>So to clarify:</p>
  
  <ol>
  <li>Report works.</li>
  <li>Change made in the merge: report  fails with #DATASYNC</li>
  <li>Merge restored as it was: report  <strong>still</strong> fails with #DATASYNC. Report needs to be completely rebuild</li>
  </ol>