Has anyone experienced this issue with AutoCAD drawings and ePDM?

Designer checks out a *.dwg file from the vault.

Designer modifies and saves the *.dwg file

Designer saves a copy of the drawing as a *.pdf

Designer checks in *.dwg & *.pdf drawing back into the vault

The vault "appears" to lose the *.dwg file and reverts to an older version (but appears to maintain the correct revision/ title blocks).. It saves a backup file with everything correct.  I have only started to investigate this issue this morning so I have not delved deeply yet. Just sending out feelers to see if any other forum members have seen this before...

Thanks