llSetRot and llSetPrimitiveParams PRIM_ROTATION are borked in child prims.
The work arounds on the JIRA and other posts to the forums may get the job done but the shocking lack of votes to have this issue fixed shows a sure unwillingness by the members of these forums to use votes for the greater good.
Relevent links are;
Please, please, please go and make a vote. You never know, LL may just get round to fixing it.