Hi Support,
I'v been struggling with your star ratings in PM 4.6. I have a DAM-environment with PM, IDI  and NX2 for NEF-files. Everything works fine in all directions when editing star-ratings initially in PM and continue editing in NX2 or IDI.
A problem occurs when re-editing the stars in PM the second time. In that case the XMP core tags (ns.adobe.com/xap...) will not been synchronized with the PM-private tags correctly.
Here is the problem: The rating has been in PM changed from initially 2 stars to 3 stars (PM-Tag moves from
 0:0:2:000445 to 0:0:3:000445). To get sure, PM has been restartet after first tag. At changing the star-rating a second time, the XMP core tags have not been updated by PM: 
<xap:Rating>2</xap:Rating> --> still at 2 and not 3 :-(
<x:xmpmeta xmlns:x="adobe:ns:meta/" x:xmptk="XMP Core 4.1.1">
   <rdf:RDF xmlns:rdf="
http://www.w3.org/1999/02/22-rdf-syntax-ns#">
      <rdf:Description rdf:about=""
            xmlns:MicrosoftPhoto="
http://ns.microsoft.com/photo/1.0">
         <MicrosoftPhoto:Rating>25</MicrosoftPhoto:Rating>
      </rdf:Description>
      <rdf:Description rdf:about=""
            xmlns:photoshop="
http://ns.adobe.com/photoshop/1.0/">
         <photoshop:DateCreated>2009-01-05</photoshop:DateCreated>
      </rdf:Description>
      <rdf:Description rdf:about=""
            xmlns:photomechanic="
http://ns.camerabits.com/photomechanic/1.0/">
         <photomechanic:TimeCreated>102411+0100</photomechanic:TimeCreated>
         <photomechanic:Prefs>
0:0:3:000445</photomechanic:Prefs>
      </rdf:Description>
      <rdf:Description rdf:about=""
            xmlns:xap="
http://ns.adobe.com/xap/1.0/">         
<xap:Rating>2</xap:Rating>      </rdf:Description>
   </rdf:RDF>
</x:xmpmeta>
At certain circumstances the core-ratings will be adopted when closing PM (but not when having sidecar files).
Any help is very much appreciated.
Regards
-Harro.