since  3 month h have big pb with " split with ground mesh" fontions ; i found a bug  who can perhups explain that .
import a  basic item like a cube (
http://supervision2.filnet.fr/froggy/ftp/obj/c1.3ds)
 
make a first rotate ( no problem)
 
make another rotate an now you have the problem
 
ps  if you make some  operation  after/before  , move , resize,  etc ...   you  have a different result : objet deformation ,  missing face , etc ..
 and i think if for that my split work one time of 100