We just migrated form clover 2.1 to 2.3.

Attached you will find a movers pdf report. As you can see all bars are totally wrong.
This report was created with the following snippet of configuration (this worked without problems in 2.1).

<historical outfile="${reports.html}/${build.date}/Code Coverage/movers1M.pdf" title="Movers: letzter Monat" historyDir="${clover.historyDir}">
<format type="pdf" />
<movers range="50" threshold="2" interval="1mo" />
</historical>