Hello,
same thing here. Our nice flowerfields (oblong sculptys) stay as a spheres.
Other sculptys do rezz normal, just the extreme streched ones doesent.
I was searching in the SL Bug - Tracker (jira) but did not find any reported issue fitting the problem so far.
Maybe VWR-24227 is similar, but i guess it is not the same reason.
So, if anyone (with more time and better english skill´s than my one) wants to verify and clear the problem out I would be glad.
It does happen with the 2.7.5 (233981) Jun 27 2011 09:26:17 (Second Life Beta Viewer).
At our shop (http://maps.secondlife.com/secondlife/Buncrana/194/148/1390) you can see flowerfields who do rezz next to more streched ones which does not.