I'm a little puzzled at the "all left arm polygons are selected in the LeftForearm group"

Do you mean that literally? If so, then there's your problem. 

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.